Photoacid generators, resist compositions, and patterning process

ABSTRACT

Photoacid generators generate sulfonic acids of formula (1a) upon exposure to high-energy radiation.
 
RC(═O)R 1 —COOCH(CF 3 )CF 2 SO 3   − H +   (1a)
 
R is hydroxyl, alkyl, aryl, hetero-aryl, alkoxy, aryloxy or hetero-aryloxy, R 1  is a divalent organic group which may have a heteroatom (O, N or S) containing substituent, or R 1  may form a cyclic structure with R. The photoacid generators are compatible with resins and can control acid diffusion and are thus suited for use in chemically amplified resist compositions.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2006-263934 filed in Japan on Sep. 28, 2006,the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to novel photoacid generators, resistcompositions comprising the same, and a patterning process using thesame.

BACKGROUND OF THE INVENTION

While a number of recent efforts are being made to achieve a finerpattern rule in the drive for higher integration and operating speeds inLSI devices, DUV and VUV lithography is thought to hold particularpromise as the next generation in microfabrication technology. Inparticular, photolithography using an ArF excimer laser as the lightsource is thought requisite to the micropatterning technique capable ofachieving a feature size of 0.13 μm or less.

The ArF lithography started partial use from the fabrication of 130-nmnode devices and became the main lithography since 90-nm node devices.Although lithography using F₂ laser (157 nm) was initially thoughtpromising as the next lithography for 45-nm node devices, itsdevelopment was retarded by several problems. A highlight was suddenlyplaced on the ArF immersion lithography that introduces a liquid havinga higher refractive index than air (e.g., water, ethylene glycol,glycerin) between the projection lens and the wafer, allowing theprojection lens to be designed to a numerical aperture (NA) of 1.0 orhigher and achieving a higher resolution. See Journal of PhotopolymerScience and Technology, Vol. 17, No. 4, p 587 (2004).

In the photolithography using an ArF excimer laser (wavelength 193 nm)as the light source, a high sensitivity resist material capable ofachieving a high resolution at a small dose of exposure is needed toprevent the degradation of precise and expensive optical systemmaterials. Among several measures for providing high sensitivity resistmaterial, the most common is to select each component which is highlytransparent at the wavelength of 193 nm. For example, polyacrylic acidand derivatives thereof, norbornene-maleic anhydride alternatingcopolymers, polynorbornene, ring-opening metathesis polymers, andhydrogenated ring-opening metathesis polymers have been proposed as thebase resin. This choice is effective to some extent in that thetransparency of a resin alone is increased.

Studies have also been made on photoacid generators. In prior artchemically amplified resist compositions for lithography using KrFexcimer laser, photoacid generators capable of generating alkane- orarene-sulfonic acid are used. However, the use of these photoacidgenerators in chemically amplified resist compositions for ArFlithography results in an insufficient acid strength to scissor acidlabile groups on the resin, a failure of resolution or a lowsensitivity. Thus these photoacid generators are not suited for thefabrication of microelectronic devices.

For the above reason, photoacid generators capable of generatingperfluoroalkanesulfonic acid having a high acid strength are generallyused in ArF chemically amplified resist compositions. These photoacidgenerators capable of generating perfluoroalkanesulfonic acid havealready been developed for use in the KrF resist compositions. Forinstance, JP-A 2000-122296 and U.S. Pat. No. 6,048,672 (or JP-A11-282168) describe photoacid generators capable of generatingperfluorohexanesulfonic acid, perfluorooctanesulfonic acid,perfluoro-4-ethylcyclohexanesulfonic acid, and perfluorobutanesulfonicacid. JP-A 2002-214774, US Patent Application Publication 2003-0113659A1 (JP-A 2003-140332), and US Patent Application Publication2002-0197558 A1 describe novel photoacid generators capable ofgenerating perfluoroalkyl ether sulfonic acids.

On the other hand, perfluorooctanesulfonic acid and homologues thereof(collectively referred to as PFOS) are considered problematic withrespect to their stability (or non-degradability) due to C—F bonds, andbiological concentration and accumulation due to hydrophobic andlipophilic natures. The US EPA adopted Significant New Use Rule, listing13 PFOS-related chemical substances and further listing 75 chemicalsubstances although their use in the photoresist field is excluded. Ithas already been proposed to apply the Rule to perfluoroalkanesulfonicacids and derivatives thereof, summing to 183 chemical substances.

Facing the PFOS-related problems, manufacturers made efforts to developpartially fluorinated alkane sulfonic acids having a reduced degree offluorine substitution. For instance, JP-A 2004-531749 describes thedevelopment of α,α-difluoroalkanesulfonic acid salts fromα,α-difluoroalkene and a sulfur compound and discloses a resistcomposition comprising a photoacid generator which generates suchsulfonic acid upon irradiation, specificallydi(4-tert-butylphenyl)iodonium1,1-difluoro-2-(1-naphthyl)ethanesulfonate. JP-A 2004-2252 describes thedevelopment of α,α,β,β-tetrafluoroalkanesulfonic acid salts fromα,α,β,β-tetrafluoro-α-iodoalkane and sulfur compound and discloses aphotoacid generator capable of generating such a sulfonic acid and aresist composition comprising the same. JP-A 2002-214774 discloses suchphotoacid generators having difluorosulfoacetic acid alkyl esters (e.g.,1-(alkoxycarbonyl)-1,1-difluoromethanesulfonate) and difluorosulfoaceticacid amides (e.g., 1-carbamoyl-1,1-difluoromethanesulfonate) althoughtheir synthesis method is lacking. Furthermore, JP-A 2005-266766discloses a photosensitive composition comprising a compound capable ofgenerating a partially fluorinated alkane sulfonic acid having asulfonylamide structure derived from perfluoroalkylene disulfonyldifluoride.

The substances disclosed in these patents have a reduced degree offluorine substitution, but suffer from several problems. They are lessdegradable because they are based on substantially undegradablehydrocarbon skeletons and they do not possess readily degradablesubstituent groups such as ester groups. A certain limit is imposed onthe molecular design for changing the size of alkanesulfonic acid. Thestarting materials containing fluorine are expensive.

With respect to the immersion lithography, there remain some problems.Minute water droplets are left on the resist and wafer after theimmersion exposure, which can often cause damages and defects to theresist pattern profile. The resist pattern after development cancollapse or deform into a T-top profile. There exists a need for apatterning process which can form a satisfactory resist pattern afterdevelopment according to the immersion lithography.

In forming fine feature size patterns, the problem of pattern densitydependency, that is, the size difference between isolated and groupedpatterns having different optical contrast becomes significant. Using aphotoacid generator capable of generating an acid with low diffusion,the problem of pattern density dependency can be overcome to someextent, but not to a satisfactory extent. While the resist compositionis required to achieve a further reduction of the pattern rule as wellas a good balance of sensitivity, substrate adhesion, and etchingresistance, it is also required to ameliorate the pattern densitydependency fundamentally without sacrifice of resolution.

DISCLOSURE OF THE INVENTION

The photoacid generator (PAG) produces an acid which must satisfy manyrequirements including a sufficient acid strength to cleave acid labilegroups in a resist material, stability in the resist material duringshelf storage, an adequate diffusion in the resist material, lowvolatility, minimal dissolution in water, no foreign matter left afterdevelopment and resist removal, and good degradability in that it isdecomposed away after the expiration of its role in lithography withoutimposing a load to the environment. No acids produced by prior art PAGssatisfy these requirements. Moreover, resist compositions using priorart photoacid generators fail to solve the problems of pattern densitydependency and line edge roughness without sacrifice of resolution.

An object of the invention is to solve the problems of prior artphotoacid generators, and to provide novel photoacid generators suitedfor use in resist materials which generators are effective in the ArFimmersion lithography due to minimized dissolution in water andcontrolled formation of foreign matter inherent to the immersionlithography, and overcome the problems of pattern density dependency andline edge roughness. Another object is to provide a resist compositionusing the photoacid generator, and a patterning process.

The inventors have found that by starting with1,1,1,3,3,3-hexafluoro-2-propanol which is readily available in theindustry, compounds having1,1,3,3,3-pentafluoro-2-acyloxypropane-1-sulfonate or1,1,3,3,3-pentafluoro-2-arylcarbonyloxypropane-1-sulfonate having acarbonyl group, carboxyl group or carboxylate ester or lactone structurecan be prepared, and that these compounds, typically onium salts, oximesand imides are effective photoacid generators in chemically amplifiedresist compositions. The present invention is predicated on thisfinding.

The present invention provides novel photoacid generators, resistcompositions and a patterning process, defined below.

-   [1] A photoacid generator for chemically amplified resist    compositions which generates a sulfonic acid upon exposure to    high-energy radiation selected from UV, deep-UV, EUV, electron beam,    x-ray, excimer laser, gamma-ray and synchrotron radiation, said    sulfonic acid having the general formula (1a):    RC(═O)R¹—COOCH(CF₃)CF₂SO₃ ⁻H⁺  (1a)    wherein R is selected from the group consisting of a hydroxyl group,    a substituted or unsubstituted straight, branched or cyclic C₁-C₂₀    alkyl group, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅    hetero-aryl group, a substituted or unsubstituted straight, branched    or cyclic C₁-C₂₀ alkoxy group, and a substituted or unsubstituted    C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent    C₁-C₂₀ organic group which may have a substituent group containing a    heteroatom selected from oxygen, nitrogen and sulfur atoms, or R¹    may form at least one cyclic structure with R.-   [2] A sulfonium salt having the general formula (2):    RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻R²R³R⁴S⁺  (2)    wherein R is selected from the group consisting of a hydroxyl group,    a substituted or unsubstituted straight, branched or cyclic C₁-C₂₀    alkyl group, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅    hetero-aryl group, a substituted or unsubstituted straight, branched    or cyclic C₁-C₂₀ alkoxy group, and a substituted or unsubstituted    C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent    C₁-C₂₀ organic group which may have a substituent group containing a    heteroatom selected from oxygen, nitrogen and sulfur atoms, or R¹    may form at least one cyclic structure with R, R², R³ and R⁴ are    each independently selected from the group consisting of substituted    or unsubstituted straight, branched or cyclic C₁-C₂₀ alkyl, alkenyl    and oxoalkyl groups, and substituted or unsubstituted C₆-C₁₈ aryl,    aralkyl and aryloxoalkyl groups, or at least two of R², R³ and R⁴    may bond together to form a ring with the sulfur atom.-   [3] A sulfonium salt having the general formula (2a):    RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻(R⁵(O)_(n))_(m)Ph′S⁺Ph₂  (2a)    wherein R is selected from the group consisting of a hydroxyl group,    a substituted or unsubstituted straight, branched or cyclic C₁-C₂₀    alkyl group, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅    hetero-aryl group, a substituted or unsubstituted straight, branched    or cyclic C₁-C₂₀ alkoxy group, and a substituted or unsubstituted    C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent    C₁-C₂₀ organic group which may have a substituent group containing a    heteroatom selected from oxygen, nitrogen and sulfur atoms, or R¹    may form at least one cyclic structure with R, R⁵ is a substituted    or unsubstituted straight, branched or cyclic C₁-C₂₀ alkyl or    alkenyl group, or a substituted or unsubstituted C₆-C₁₄ aryl group,    m is an integer of 1 to 5, n is 0 or 1, Ph is phenyl, and Ph′ is a    phenyl group in which a number “m” of hydrogen atoms are substituted    by R⁵(O)_(n)— groups.-   [4] A iodonium salt having the general formula (2b):    RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻[(R⁵(O)_(n))_(m)Ph′]₂I⁺  (2b)    wherein R is selected from the group consisting of a hydroxyl group,    a substituted or unsubstituted straight, branched or cyclic C₁-C₂₀    alkyl group, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅    hetero-aryl group, a substituted or unsubstituted straight, branched    or cyclic C₁-C₂₀ alkoxy group, and a substituted or unsubstituted    C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent    C₁-C₂₀ organic group which may have a substituent group containing a    heteroatom selected from oxygen, nitrogen and sulfur atoms, or R¹    may form at least one cyclic structure with R, R⁵ is a substituted    or unsubstituted straight, branched or cyclic C₁-C₂₀ alkyl or    alkenyl group, or a substituted or unsubstituted C₆-C₁₄ aryl group,    m is an integer of 1 to 5, n is 0 or 1, and Ph′ is a phenyl group in    which a number “m” of hydrogen atoms are substituted by R⁵(O)_(n)—    groups.-   [5] A N-sulfonyloxyimide compound having the general formula (3a):

wherein R is selected from the group consisting of a hydroxyl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkylgroup, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-arylgroup, a substituted or unsubstituted straight, branched or cyclicC₁-C₂₀ alkoxy group, and a substituted or unsubstituted C₆-C₁₅ aryloxyor C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic groupwhich may have a substituent group containing a heteroatom selected fromoxygen, nitrogen and sulfur atoms, or R¹ may form at least one cyclicstructure with R, X and Y are each independently hydrogen or asubstituted or unsubstituted C₁-C₆ alkyl group, or X and Y may bondtogether to form a saturated or unsaturated C₆-C₁₂ ring with the carbonatoms to which they are attached, and Z is a single bond, double bond,methylene group or oxygen atom.

-   [6] An oxime sulfonate compound having the general formula (3b):

wherein R is selected from the group consisting of a hydroxyl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkylgroup, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-arylgroup, a substituted or unsubstituted straight, branched or cyclicC₁-C₂₀ alkoxy group, and a substituted or unsubstituted C₆-C₁₅ aryloxyor C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic groupwhich may have a substituent group containing a heteroatom selected fromoxygen, nitrogen and sulfur atoms, or R¹ may form at least one cyclicstructure with R, q is 0 or 1, when q is 0, p is a substituted orunsubstituted C₁-C₂₀ alkyl group or a substituted or unsubstitutedC₆-C₁₅ aryl group, when q is 1, p is a single bond, a substituted orunsubstituted C₁-C₂₀ alkylene group or a substituted or unsubstitutedC₆-C₁₅ arylene group, EWG is a cyano, trifluoromethyl, perfluoroethyl,perfluoropropyl, 5H-perfluoropentyl, 6H-perfluorohexyl, nitro or methylgroup, and when q is 1, two EWG's may bond together to form a ring of 6carbon atoms with the carbon atoms to which they are attached.

-   [7] A resist composition comprising a base resin, an acid generator,    and an organic solvent, said acid generator comprising a photoacid    generator which generates a sulfonic acid having formula (1a) as set    forth in [1].-   [8] The resist composition of [7], wherein said base resin is at    least one polymer selected from the group consisting of    poly(meth)acrylic acid and derivatives thereof, cycloolefin    derivative/maleic anhydride alternating copolymers, copolymers of    ternary or more components comprising a cycloolefin derivative,    maleic anhydride, and polyacrylic acid or derivatives thereof,    cycloolefin derivative/α-trifluoromethyl acrylate derivative    copolymers, polynorbornene, ring-opening metathesis polymers, and    hydrogenated ring-opening metathesis polymers.-   [9] The resist composition of [7], wherein said base resin is a    polymeric structure containing silicon atoms.-   [10] The resist composition of [7], wherein said base resin is a    polymeric structure containing fluorine atoms.-   [11] A chemically amplified positive resist composition comprising a    base resin as set forth in [8], [9] or [10], a photoacid generator    which generates a sulfonic acid having formula (1a) as set forth in    [1], and a solvent, wherein said base resin is insoluble or    substantially insoluble in a liquid developer, and becomes soluble    under the action of the acid.-   [12] The chemically amplified positive resist composition of [11],    further comprising a quencher.-   [13] The chemically amplified positive resist composition of [11] or    [12], further comprising a dissolution inhibitor.-   [14] A process for forming a pattern comprising the steps of    applying the resist composition of any one of [7] to [13] onto a    substrate to form a coating, heat treating the coating and exposing    it to high-energy radiation having a wavelength of up to 300 nm    through a photomask, and optionally heat treating and developing the    exposed coating with a developer.-   [15] The process of [14], wherein the exposing step relies on    immersion lithography comprising directing radiation from an ArF    excimer laser having a wavelength of 193 nm through a projection    lens, with a liquid such as water, glycerin or ethylene glycol    intervening between the coated substrate and the projection lens.

BENEFITS OF THE INVENTION

Since the photoacid generators of the invention include a carbonylgroup, carboxyl group, carboxylate ester or lactone structure in thesulfonate in addition to an acyloxy or arylcarbonyloxy group atβ-position, they are fully compatible with resins and other componentsin resist compositions and enable to control acid diffusion. Thephotoacid generators that generate these sulfonic acids perform wellwithout raising problems during the device fabrication process includingcoating, pre-baking, exposure, post-exposure baking, and developingsteps. The dissolution of sulfonic acids in water during the ArFimmersion lithography is minimized. The influence of water left on thewafer is minimized, restraining defects from forming. In the disposal ofresist-containing waste liquid after the device fabrication, acyloxy orarylcarbonyloxy groups at β-position are hydrolyzable under basicconditions so that the sulfonic acids are transformed into lessaccumulative compounds of lower molecular weight. In the disposal bycombustion, the sulfonic acids are more combustible because of a lowdegree of fluorine substitution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-A inSynthesis Example 19.

FIG. 2 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-A inSynthesis Example 19.

FIG. 3 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-B inSynthesis Example 20.

FIG. 4 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-B inSynthesis Example 20.

FIG. 5 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-C inSynthesis Example 21.

FIG. 6 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-C inSynthesis Example 21.

FIG. 7 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-Y inSynthesis Example 43.

FIG. 8 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-Y inSynthesis Example 43.

FIG. 9 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-Z1 inSynthesis Example 44.

FIG. 10 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-Z1 inSynthesis Example 44.

FIG. 11 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-Z2 inSynthesis Example 45.

FIG. 12 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-Z2 inSynthesis Example 45.

FIG. 13 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-Z3 inSynthesis Example 46.

FIG. 14 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-Z3 inSynthesis Example 46.

FIG. 15 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG-Z4 inSynthesis Example 47.

FIG. 16 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG-Z4 inSynthesis Example 47.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The singular forms “a,” “an” and “the” include plural referents unlessthe context clearly dictates otherwise.

The notation (Cn-Cm) means a group containing from n to m carbon atomsper group.

Photoacid Generator

The photoacid generators of the invention are compounds, typicallysulfonium salts, iodonium salts, oxime sulfonates and sulfonyloxyimides.These compounds are sensitive to high-energy radiation such as UV,deep-UV, electron beam, EUV, x-ray, excimer laser, gamma-ray andsynchrotron radiation and generate sulfonic acids having the generalformula (1a) in response to high-energy radiation, so that they areuseful as photoacid generators in chemically amplified resistcompositions.RC(═O)R¹—COOCH(CF₃)CF₂SO₃ ⁻H⁺  (1a)Herein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom selected from oxygen, nitrogen and sulfur atoms,or R¹ may form at least one cyclic structure with R.

In formula (1a), R is a hydroxyl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkyl group, a substituted orunsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted orunsubstituted straight, branched or cyclic C₁-C₂₀ alkoxy group, or asubstituted or unsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxygroup; R¹ is a divalent C₁-C₂₀ organic group which may have asubstituent group containing a heteroatom such as an oxygen, nitrogen orsulfur atom, or R¹ may form one or more cyclic structures with R.Suitable substituent groups on the groups represented by R includehydroxyl groups, alkoxy groups, aryloxy groups, fluorine atoms, chlorineatoms, bromine atoms, iodine atoms, carboxyl groups, alkoxycarbonylgroups, amide groups, carbonyl groups, ether-bonding oxygen atoms andthe like. Where R is an alkyl group, at least one hydrogen atom thereonmay be replaced by an aryl group. Where R is an aryl group, at least onehydrogen atom thereon may be replaced by an alkyl group.

Illustrative examples of the groups represented by R include hydroxyl,methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, sec-butyl,isobutyl, tert-butyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl,n-octyl, n-decyl, n-dodecyl, 1-adamantyl, 2-adamantyl,bicyclo[2.2.1]hepten-1-yl, 1-adamantanemethyl, 2-adamantanemethyl,phenyl, 4-methoxyphenyl, 4-tert-butylphenyl, 4-biphenyl, 1-naphthyl,2-naphthyl, 10-anthranyl, 2-furanyl, methoxy, ethoxy, n-propoxy,isopropoxy, cyclopropyloxy, n-butoxy, sec-butoxy, isobutoxy,tert-butoxy, n-pentyloxy, cyclopentyloxy, n-hexyloxy, cyclohexyloxy,n-octyloxy, n-decyloxy, n-dodecyloxy, 1-adamantyloxy, 2-adamantyloxy,bicyclo[2.2.1]hepten-2-yloxy, 1-adamantanemethoxy, 2-adamantanemethoxy,phenoxy, 4-methoxyphenyloxy, 4-tert-butylphenyloxy, 4-biphenyloxy,1-naphthyloxy, 2-naphthyloxy, 10-anthranyloxy, 2-furanyloxy,2,2,2-trifluoroethoxy, 1,1,1,3,3,3-hexafluoro-2-propyloxy, and2,2,3,3-tetrafluoropropoxy. Inter alia, hydroxyl, methoxy, cyclohexyloxyand 1-adamantanemethoxy groups are preferred.

R¹ is a divalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom such as an oxygen, nitrogen or sulfur atom, orR¹ may form a cyclic structure with R. Suitable substituent groups onthe groups represented by R¹ include hydroxyl groups, alkoxy groups,aryloxy groups, fluorine atoms, chlorine atoms, bromine atoms, iodineatoms, carboxyl groups, alkoxycarbonyl groups, amide groups, carbonylgroups, ether-bonding oxygen atoms and the like. Illustrative examplesof the groups represented by R¹ include methylene, ethylene,1,3-propylene, 1,2-propylene, isopropylidene, 1,4-butylene,1,6-hexylene, o-phenylene, m-phenylene, and p-phenylene, as well asthose of the structures shown below. In the structural formulae, thebroken line denotes a bonding site.

Of these, preference is given to ethylene, 1,3-propylene and those ofthe structures shown below.

When R and R¹ bond together to form a cyclic structure, exemplarystructures are illustrated below.

Illustrative examples of the sulfonic acids of formula (1a) are shownbelow.

Sulfonium Salt

The sulfonium salt of the invention has the general formula (2):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ^(−R) ²R³R⁴S⁺  (2)wherein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom such as an oxygen, nitrogen or sulfur atom, orR¹ may form at least one cyclic structure with R; R², R³ and R⁴ are eachindependently a substituted or unsubstituted straight, branched orcyclic C₁-C₂₀ alkyl, alkenyl or oxoalkyl group, or a substituted orunsubstituted C₆-C₁₈ aryl, aralkyl or aryloxoalkyl group, or at leasttwo of R², R³ and R⁴ may bond together to form a ring with the sulfuratom.

In formula (2), R and R¹ are as defined and illustrated above. R², R³and R⁴ are each independently a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl, alkenyl or oxoalkyl group, or asubstituted or unsubstituted C₆-C₁₈ aryl, aralkyl or aryloxoalkyl group,or any two or more of R², R³ and R⁴ may bond together to form a ringwith the sulfur atom. Suitable alkyl groups include methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl,heptyl, octyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl,4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl. Suitablealkenyl groups include vinyl, allyl, propenyl, butenyl, hexenyl, andcyclohexenyl. Suitable oxoalkyl groups include 2-oxocyclopentyl,2-oxocyclohexyl, 2-oxopropyl, 2-oxoethyl, 2-cyclopentyl-2-oxoethyl,2-cyclohexyl-2-oxoethyl, and 2-(4-methylcyclohexyl)-2-oxoethyl. Suitablearyl groups include phenyl, naphthyl, and thienyl; 4-hydroxyphenyl;alkoxyphenyl groups such as 4-methoxyphenyl, 3-methoxyphenyl,2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and3-tert-butoxyphenyl; alkylphenyl groups such as 2-methylphenyl,3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl,4-n-butylphenyl, and 2,4-dimethylphenyl; alkylnaphthyl groups such asmethylnaphthyl and ethylnaphthyl; alkoxynaphthyl groups such asmethoxynaphthyl and ethoxynaphthyl; dialkylnaphthyl groups such asdimethylnaphthyl and diethylnaphthyl; and dialkoxynaphthyl groups suchas dimethoxynaphthyl and diethoxynaphthyl. Suitable aralkyl groupsinclude benzyl, 1-phenylethyl and 2-phenylethyl. Suitable aryloxoalkylgroups include 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. When two ormore of R², R³ and R⁴ bond together to form a cyclic structure with thesulfur atom, divalent organic groups such as 1,4-butylene and3-oxa-1,5-pentylene are exemplary of the cyclic structure-forming group.Also included are aryl groups having polymerizable substituent radicalssuch as acryloyloxy and methacryloyloxy radicals, and examples of sucharyl groups are 4-acryloyloxyphenyl, 4-methacryloyloxyphenyl,4-acryloyloxy-3,5-dimethylphenyl, 4-methacryloyloxy-3,5-dimethylphenyl,4-vinyloxyphenyl, and 4-vinylphenyl groups.

Illustrative examples of the sulfonium cation includetriphenylsulfonium, 4-hydroxyphenyldiphenylsulfonium,bis(4-hydroxyphenyl)phenylsulfonium, tris(4-hydroxyphenyl)sulfonium,4-tert-butoxyphenyldiphenylsulfonium,bis(4-tert-butoxyphenyl)phenylsulfonium,tris(4-tert-butoxyphenyl)sulfonium, 3-tert-butoxyphenyldiphenylsulfoniumbis(3-tert-butoxyphenyl)phenylsulfonium,tris(3-tert-butoxyphenyl)sulfonium,3,4-di-tert-butoxyphenyldiphenylsulfonium,bis(3,4-di-tert-butoxyphenyl)phenylsulfonium,tris(3,4-di-tert-butoxyphenyl)sulfonium,diphenyl(4-thiophenoxyphenyl)sulfonium,4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium,tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium,(4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium,tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium,(4-hydroxy-3,5-dimethylphenyl)diphenylsulfonium,(4-n-hexyloxy-3,5-dimethylphenyl)diphenylsulfonium,dimethyl(2-naphthyl)sulfonium, 4-hydroxyphenyldimethylsulfonium,4-methoxyphenyldimethylsulfonium, trimethylsulfonium,2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium,tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium,2-oxo-2-phenylethylthiacyclopentanium, diphenyl-2-thienylsulfonium,4-n-butoxynaphthyl-1-thiacyclopentanium,2-n-butoxynaphthyl-1-thiacyclopentanium,4-methoxynaphthyl-1-thiacyclopentanium, and2-methoxynaphthyl-1-thiacyclopentanium. Preferred cations aretriphenylsulfonium, 4-tert-butylphenyldiphenylsulfonium,4-tert-butoxyphenyldiphenylsulfonium, tris(4-tert-butylphenyl)sulfonium,and 4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium. Also includedare 4-methacryloyloxyphenyldiphenylsulfonium,4-acryloyloxyphenyldiphenylsulfonium,4-methacryloyloxyphenyldimethylsulfonium,4-acryloyloxyphenyldimethylsulfonium,(4-methacryloyloxy-3,5-dimethylphenyl)diphenylsulfonium,(4-acryloyloxy-3,5-dimethylphenyl)diphenylsulfonium, and the like. Forthese polymerizable sulfonium cations, reference may be made to JP-A4-230645 and JP-A 2005-84365. These polymerizable sulfonium salts may beused as a monomer in forming a polymer to be described later.

Another embodiment is a sulfonium salt having the general formula (2a):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻(R⁵(O)_(n))_(m)Ph′S⁺Ph₂  (2a)wherein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom such as an oxygen, nitrogen or sulfur atom, orR¹ may form at least one cyclic structure with R; R⁵ is a substituted orunsubstituted straight, branched or cyclic C₁-C₂₀ alkyl or alkenylgroup, or a substituted or unsubstituted C₆-C₁₄ aryl group; m is aninteger of 1 to 5, n is 0 or 1; Ph is phenyl, and Ph′ is a phenyl groupin which a number “m” of hydrogen atoms are substituted by R⁵(O)_(n)—groups.

In formula (2a), R and R¹ are as defined and illustrated above. Thesubstitution position of R⁵—(O)_(n)— group is not particularly limited,but is preferably 4- or 3-position on the phenyl group, and morepreferably 4-position. Examples of groups represented by R⁵ includemethyl, ethyl, n-propyl, sec-propyl, cyclopropyl, n-butyl, sec-butyl,isobutyl, tert-butyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl,n-octyl, n-decyl, n-dodecyl, trifluoromethyl, phenyl, 4-methoxyphenyl,and 4-tert-butylphenyl. In the case of n=1, acryloyl, methacryloyl,vinyl, and allyl are exemplary of R⁵. The letter m is an integer of 1 to5, and preferably 1, and n is 0 (zero) or 1.

Illustrative examples of the sulfonium cation include4-methylphenyldiphenylsulfonium, 4-ethylphenyldiphenylsulfonium,4-tert-butylphenyldiphenylsulfonium,4-cyclohexylphenyldiphenylsulfonium, 4-n-hexylphenyldiphenylsulfonium,4-n-octylphenyldiphenylsulfonium, 4-methoxyphenyldiphenylsulfonium,4-ethoxyphenyldiphenylsulfonium, 4-tert-butoxyphenyldiphenylsulfonium,4-cyclohexyloxyphenyldiphenylsulfonium,4-n-hexyloxyphenyldiphenylsulfonium,4-n-octyloxyphenyldiphenylsulfonium,4-dodecyloxyphenyldiphenylsulfonium,4-trifluoromethylphenyldiphenylsulfonium,4-trifluoromethyloxyphenyldiphenylsulfonium,4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium,4-methacryloyloxyphenyldiphenylsulfonium,4-acryloyloxyphenyldiphenylsulfonium,(4-n-hexyloxy-3,5-dimethylphenyl)diphenylsulfonium,(4-methacryloyloxy-3,5-dimethylphenyl)diphenylsulfonium, and(4-acryloyloxy-3,5-dimethylphenyl)diphenylsulfonium.

Iodonium Salt

A further embodiment of the invention is a iodonium salt having thegeneral formula (2b):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻[(R⁵(O)_(n))_(m)Ph′]₂I⁺  (2b)wherein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom selected from oxygen, nitrogen and sulfur atoms,or R¹ may form at least one cyclic structure with R; R⁵ is a substitutedor unsubstituted straight, branched or cyclic C₁-C₂₀ alkyl or alkenylgroup, or a substituted or unsubstituted C₆-C₁₄ aryl group; m is aninteger of 1 to 5, n is 0 or 1; and Ph′ is as defined above.

In formula (2b), R, R¹, R⁵, n and m are as defined and illustratedabove. The substitution position of R⁵—(O)_(n)— group is notparticularly limited, but is preferably 4- or 3-position on the phenylgroup, and more preferably 4-position.

Illustrative examples of the iodonium cation includebis(4-methylphenyl)iodonium, bis(4-ethylphenyl)iodonium,bis(4-tert-butylphenyl)iodonium,bis(4-(1,1-dimethylpropyl)phenyl)iodonium,4-methoxyphenylphenyliodonium, 4-tert-butoxyphenylphenyliodonium,4-acryloyloxyphenylphenyliodonium, and4-methacryloyloxyphenylphenyliodonium, with thebis(4-tert-butylphenyl)iodonium being preferred.

N-sulfonyloxyimide

A further embodiment of the invention is a N-sulfonyloxyimide compoundhaving the general formula (3a):

wherein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom such as an oxygen, nitrogen or sulfur atom, orR¹ may form at least one cyclic structure with R; X and Y are eachindependently hydrogen or a substituted or unsubstituted C₁-C₆ alkylgroup, or X and Y may bond together to form a saturated or unsaturatedC₆-C₁₂ ring with the carbon atoms to which they are attached; and Z is asingle bond, double bond, methylene group or oxygen atom.

In formula (3a), R and R¹ are as defined and illustrated above. X and Yare each independently hydrogen or a substituted or unsubstituted C₁-C₆alkyl group, or X and Y may bond together to form a saturated orunsaturated C₆-C₁₂ ring with the carbon atoms to which they areattached, and Z is a single bond, double bond, methylene group or oxygenatom. Illustrative examples of the imide skeleton excluding thesulfonate moiety are given below. For the imide skeleton, reference maybe made to JP-A 2003-252855.

Oxime Sulfonate

A further embodiment of the invention is an oxime sulfonate compoundhaving the general formula (3b):

wherein R is a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, or a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group; R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom such as an oxygen, nitrogen or sulfur atom, orR¹ may form at least one cyclic structure with R; q is 0 or 1; when q is0, p is a substituted or unsubstituted C₁-C₂₀ alkyl group or asubstituted or unsubstituted C₆-C₁₅ aryl group, and when q is 1, p is asingle bond, a substituted or unsubstituted C₁-C₂₀ alkylene group or asubstituted or unsubstituted C₆-C₁₅ arylene group; EWG is a cyano,trifluoromethyl, perfluoroethyl, perfluoropropyl, 5H-perfluoropentyl,6H-perfluorohexyl, nitro or methyl group, and when q is 1, two EWG's maybond together to form a ring of 6 carbon atoms with the carbon atoms towhich they are attached.

In formula (3b), R and R¹ are as defined and illustrated above. When qis equal to 0, p is a substituted or unsubstituted C₁-C₂₀ alkyl group ora substituted or unsubstituted C₆-C₁₅ aryl group. When q is equal to 1,p is a single bond, a substituted or unsubstituted C₁-C₂₀ alkylene groupor a substituted or unsubstituted C₆-C₁₅ arylene group. EWG is a cyano,trifluoromethyl, perfluoroethyl, perfluoropropyl, 5H-perfluoropentyl,6H-perfluorohexyl, nitro or methyl group. When q is equal to 1, twoEWG's may bond together to form a ring of 6 carbon atoms with the carbonatoms to which they are attached. The skeletons of the oxime sulfonatesare described in U.S. Pat. No. 6,261,738, JP-A 9-95479, JP-A 9-208554,JP-A 9-230588, Japanese Patent No. 2,906,999, JP-A 9-301948, JP-A2000-314956, JP-A 2001-233842, and International Publication2004/074242.

Exemplary skeletons of oxime sulfonates excluding the sulfonate moietyare given below.

Described below is how to synthesize the foregoing photoacid generatorscapable of generating a sulfonic acid of formula (1a).

The synthesis of sulfonium salt having formula (2) as a first example ofthe photoacid generator starts with triphenylsulfonium1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, synthesized as will bedescribed later, and an aliphatic carboxylic acid halide or anhydride,aromatic carboxylic acid halide or anhydride, aliphatic dicarboxylicanhydride, or aromatic dicarboxylic anhydride, each having a carboxylateester or lactone structure. By reacting them under basic conditions, asulfonium salt having a carboxylate ester or lactone structure or acarbonyl or carboxyl group as represented by formula (2) can beprepared.

The sulfonium and iodonium salts of formulae (2a) and (2b) can besynthesized by the same process as described above.

The synthesis of the imide sulfonate and oxime sulfonate of formulae(3a) and (3b) starts with an imide sulfonate or oxime sulfonate having a1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate moiety and an aliphaticcarboxylic acid halide or anhydride, aromatic carboxylic acid halide oranhydride, aliphatic dicarboxylic anhydride, or aromatic dicarboxylicanhydride, each having a carboxylate ester or lactone structure. Byreacting them under basic conditions, an imide sulfonate or oximesulfonate having a carboxylate ester or lactone structure or a carbonylor carboxyl group can be prepared.

Briefly noted herein is the synthesis of triphenylsulfonium1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate. First, an aliphatic oraromatic carboxylic acid ester of 1,1,3,3,3-pentafluoropropen-2-yl,typically 1,1,3,3,3-pentafluoropropen-2-yl benzoate, which was developedby Nakai et al. using 1,1,1,3,3,3-hexafluoro-2-propanol as the startingreactant, is reacted with sodium hydrogen sulfite or sodium sulfite in asolvent such as water or alcohol or a mixture thereof in the presence ofa radical initiator such as azobisisobutyronitrile or benzoyl peroxide,forming a corresponding 1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonicacid salt or 1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonicacid salt. This salt is ion-exchanged with a suitable sulfonium salt,forming triphenylsulfonium1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonate or triphenylsulfonium1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonate. Thecarboxylate moiety of the sulfonate is then subjected to hydrolysis withthe aid of an alkali such as sodium hydroxide or potassium hydroxide, orsolvolysis with the aid of an alcohol and base, yielding the targetcompound, triphenylsulfonium1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate.

Salts of sulfonium other than triphenylsulfonium and iodonium may besimilarly synthesized.

The synthesis of an imide sulfonate or oxime sulfonate having a1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate moiety is as follows.

First, 1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonate salt or1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonate salt is reactedwith a chlorinating agent such as thionyl chloride, phosphorusoxychloride or phosphorus pentachloride to form a corresponding sulfonylchloride or sulfonic acid anhydride. This is further reacted withN-hydroxydicarboxylimide or oxime in a conventional way, forming1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonate or1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonate. This isfollowed by hydrolysis of the acyloxy or arenecarbonyloxy group, formingthe desired intermediate, imide sulfonate or oxime sulfonate having a1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate moiety.

The starting sulfonium and iodonium salts can be synthesized inaccordance with the teachings of The Chemistry of Sulfonium Group Part1, John-Wiley & Sons (1981), Advanced Photochemistry, Vol. 17,John-Wiley & Sons (1992), J. Org. Chem., 53, 5571-5573, 1988, JP-A8-311018, JP-A 9-15848, JP-A 2001-122850, JP-A 7-25846, JP-A2001-181221, JP-A 2002-193887, and JP-A 2002-193925. The onium cationhaving an acryloyloxy or methacryloyloxy group as the polymerizablesubstituent group can be synthesized by reacting (currently available)hydroxyphenyldiphenylsulfonium halide with acryloyl chloride ormethacryloyl chloride under basic conditions according to the methodsdescribed in JP-A 4-230645 and JP-A 2005-84365.

For the synthesis of imide sulfonate or oxime sulfonate, referenceshould be made to the above-cited JP-A 2003-252855, U.S. Pat. No.6,261,738, JP-A 9-95479, JP-A 9-208554, JP-A 9-230588, Japanese PatentNo. 2,906,999, JP-A 9-301948, JP-A 2000-314956, JP-A 2001-233842, andInternational Publication 2004-074242.

As described above, a first embodiment of the present invention providesa photoacid generator for chemically amplified resist compositions whichgenerates a sulfonic acid having formula (1a) upon exposure tohigh-energy radiation. A second embodiment of the present inventionprovides a sulfonium salt, iodonium salt, dicarboxylimide sulfonate, andoxime sulfonate serving as photoacid generators in chemically amplifiedresist compositions. A third embodiment of the present inventionprovides a resist composition comprising a photoacid generator whichgenerates a sulfonic acid having formula (1a) upon exposure tohigh-energy radiation and a resin which changes its solubility in analkaline developer liquid under the action of acid.

The resist composition of the invention is typically embodied as

-   (i) a chemically amplified positive resist composition comprising

(A) a photoacid generator which generates a sulfonic acid having formula(1a) upon exposure to high-energy radiation,

(B) an organic solvent,

(C) a base resin which changes its solubility in an alkaline developerliquid under the action of acid, and

one or more optional components including (D) a quencher, (E) aphotoacid generator other than (A), (F) an organic acid derivativeand/or fluorinated alcohol, and (G) a dissolution inhibitor having aweight average molecular weight of up to 3,000; and

-   (ii) a chemically amplified negative resist composition comprising

(A) a photoacid generator which generates a sulfonic acid having formula(1a) upon exposure to high-energy radiation,

(B) an organic solvent,

(C′) a base resin which is normally alkali soluble, but becomessubstantially alkali insoluble under the action of a crosslinker,

(H) a crosslinker which induces crosslinkage under the action of acid,and

one or more optional components including (D) a quencher and (E) aphotoacid generator other than (A).

The PAG which generates a sulfonic acid having formula (1a) as component(A) is as described above. More specifically, it is a compound havingformula (2), (2a), (2b), (3a) or (3b). In the resist composition, thePAG is compounded in an amount of 0.1 to 10 parts, more preferably 1 to7 parts by weight per 100 parts by weight of the base resin. Note thatparts by weight per 100 parts by weight of the resin is oftenabbreviated as “phr”.

Component B

The organic solvent used herein may be any organic solvent in which thebase resin, photoacid generator, and other components are soluble.Illustrative, non-limiting, examples of the organic solvent includeketones such as cyclohexanone and methyl amyl ketone; alcohols such as3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether,ethylene glycol monomethyl ether, propylene glycol monoethyl ether,ethylene glycol monoethyl ether, propylene glycol dimethyl ether, anddiethylene glycol dimethyl ether; esters such as propylene glycolmonomethyl ether acetate (PGMEA), propylene glycol monoethyl etheracetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate,tert-butyl propionate, and propylene glycol mono-tert-butyl etheracetate; and lactones such as γ-butyrolactone. These solvents may beused alone or in combinations of two or more thereof. Of the aboveorganic solvents, it is recommended to use diethylene glycol dimethylether, 1-ethoxy-2-propanol, PGMEA, cyclohexanone and mixtures thereofbecause the photoacid generator is most soluble therein.

An appropriate amount of the organic solvent used is about 200 to 3,000parts, especially about 400 to 2,000 parts by weight per 100 parts byweight of the base resin.

Component C

The base resins used as component (C) or (C′) in the inventivecompositions include polyhydroxystyrene (PHS), and copolymers of PHSwith styrene, (meth)acrylic acid esters or other polymerizable olefiniccompounds, for KrF excimer laser resist use; (meth)acrylic acid esterpolymers, alternating copolymers of cycloolefin with maleic anhydrideand similar copolymers further containing vinyl ethers or (meth)acrylicacid esters, polynorbornene, ring-opening metathesis polymerizedcycloolefins, and hydrogenated ring-opening metathesis polymerizedcycloolefins, for ArF excimer laser resist use; and fluorinated forms ofthe foregoing polymers (for both KrF and ArF laser uses) for F₂ excimerlaser resist use, although the base resins are not limited to thesepolymers. Understandably, the sulfonium salts and iodonium salts havingpolymerizable substituent groups according to the invention may be usedas a monomer component in forming the base resin. Typical sulfonium andiodonium salts for such use are combinations of onium cations such as(4-acryloyloxyphenyl)diphenylsulfonium,(4-methacryloyloxyphenyl)diphenylsulfonium,(4-acryloyloxyphenyl)phenyliodonium, and(4-methacryloyloxyphenyl)phenyliodonium cations with anions such as1-(difluorosulfomethyl)-2,2,2-trifluoroethyl hydrogencyclohexanedicarboxylate. The base resins may be used alone or inadmixture of two or more. In the case of positive resist compositions,it is a common practice to substitute acid labile groups for hydroxylgroups on phenols, carboxyl groups or fluorinated alkyl alcohols forreducing the rate of dissolution in unexposed regions.

The base resins are not limited to the foregoing resins. Use may also bemade of the resins described in the following patents.

JP-A 2000-159758 corresponding to U.S. Pat. No. 6,280,898 B1

JP-A 2000-186118 corresponding to U.S. Pat. No. 6,147,249 A

JP-A 2000-309611 corresponding to U.S. Pat. No. 6,284,429 B1

JP-A 2000-327633 corresponding to U.S. Pat. No. 6,448,420 B1

JP-A 2000-330283 corresponding to U.S. Pat. No. 6,413,695 B1

JP-A 2001-329052 corresponding to U.S. Pat. No. 6,509,135 B2

JP-A 2002-202609 corresponding to U.S. Pat. No. 6,605,408 B2

JP-A 2002-161116 corresponding to U.S. Pat. No. 6,673,515 B2

JP-A 2003-002883 corresponding to U.S. Pat. No. 6,517,994 B2

JP-A 2003-020313 corresponding to US 2003/0050398 A1

JP-A 2003-026728

JP-A 2003-034706 corresponding to U.S. Pat. No. 6,794,111 B2

JP-A 2003-064134 corresponding to U.S. Pat. No. 6,673,518 B2

JP-A 2003-066612 corresponding to U.S. Pat. No. 6,830,866

JP-A 2003-113213 corresponding to U.S. Pat. No. 6,946,233 B2

JP-A 2003-316027 corresponding to U.S. Pat. No. 6,878,508 B2

JP-A 2003-321466 corresponding to U.S. Pat. No. 7,090,961 B2

JP-A 2004-143153 corresponding to U.S. Pat. No. 7,132,215 B2

JP-A 2004-124082 corresponding to U.S. Pat. No. 6,312,867 B1

JP-A 2004-115486 corresponding to U.S. Pat. No. 7,037,995 B2

JP-A 2004-062175 corresponding to U.S. Pat. No. 6,312,867 B1

In a preferred embodiment, the base resin is at least one polymerselected from among poly(meth)acrylic acid and derivatives thereof,cycloolefin derivative/maleic anhydride alternating copolymers,copolymers of three or more components comprising a cycloolefinderivative, maleic anhydride, and polyacrylic acid or derivativesthereof, cycloolefin derivative/α-trifluoromethyl acrylate copolymers,polynorbornene, ring-opening metathesis polymers, and hydrogenatedring-opening metathesis polymers.

In another preferred embodiment, the base resin is a polymeric structurecontaining silicon atoms or a polymeric structure containing fluorineatoms. Such polymers include those described in the following patents.

JP-A 2005-008765

JP-A 2004-354417 corresponding to US 2004/0241579 A1

JP-A 2004-352743 corresponding to U.S. Pat. No. 6,994,946 B2

JP-A 2004-331854

JP-A 2004-331853

JP-A 2004-292781

JP-A 2004-252405

JP-A 2004-190036 corresponding to U.S. Pat. No. 6,309,796 B1

JP-A 2004-115762 corresponding to U.S. Pat. No. 7,192,684 B2

JP-A 2004-083873 corresponding to U.S. Pat. No. 6,919,161 B2

JP-A 2004-059844 corresponding to US 2004/0023176 A1

JP-A 2004-035671 corresponding to U.S. Pat. No. 6,902,772 B2

JP-A 2004-083900 corresponding to U.S. Pat. No. 7,125,943 B2

JP-A 2004-099689

JP-A 2004-145048 corresponding to U.S. Pat. No. 6,875,556 B2

JP-A 2004-217533 corresponding to US 2004/0192867 A1

JP-A 2004-231815 corresponding to US 2006/0074263A1

JP-A 2004-244439 corresponding to U.S. Pat. No. 7,125,641 B2

JP-A 2004-256562

JP-A 2004-307447 corresponding to U.S. Pat. No. 6,858,760 B2

JP-A 2004-323422 corresponding to US 2006/0135744 A1

JP-A 2005-029527 corresponding to U.S. Pat. No. 7,232,917 B2

JP-A 2005-029539 corresponding to US 2006/0217507 A1

Included in the chemically amplified positive resist composition is abase resin having acid labile groups which is normally insoluble orsubstantially insoluble in developer, but becomes soluble in developeras a result of the acid labile groups being eliminated under the actionof acid.

The acid labile groups to be introduced into the base resin may beselected from a variety of such groups, preferably from C₂-C₃₀ acetalgroups and tertiary C₄-C₃₀ alkyl groups having the formulae (C1) and(C2), respectively.

In formulae (C1) and (C2), R²⁰¹ and R²⁰² each are hydrogen or astraight, branched or cyclic C₁-C₂₀ alkyl group, which may contain ahetero atom such as oxygen, sulfur, nitrogen or fluorine, R²⁰³, R³⁰⁴,R²⁰⁵ and R²⁰⁶ each are a straight, branched or cyclic C₁-C₂₀ alkylgroup, a C₆-C₁₀ aryl group or a C₇-C₁₀ aralkyl group, which may containa hetero atom such as oxygen, sulfur, nitrogen or fluorine. A pair ofR²⁰¹ and R²⁰², a pair of R²⁰¹ and R²⁰³, a pair of R²⁰² and R²⁰³, a pairof R²⁰⁴ and R²⁰⁵, a pair of R²⁰⁴ and R²⁰⁶, or a pair of R and R²⁰⁶,taken together, may form a ring of 3 to 30 carbon atoms with the carbonatom or the carbon and oxygen atoms to which they are attached.

Illustrative examples of the acetal group of formula (C1) include, butare not limited to, methoxymethyl, ethoxymethyl, propoxymethyl,butoxymethyl, isopropoxymethyl, t-butoxymethyl, 1-methoxyethyl,1-methoxypropyl, 1-methoxybutyl, 1-ethoxyethyl, 1-ethoxypropyl,1-ethoxybutyl, 1-propoxyethyl, 1-propoxypropyl, 1-propoxybutyl,1-cyclopentyloxyethyl, 1-cyclohexyloxyethyl, 2-methoxyisopropyl,2-ethoxyisopropyl, 1-phenoxyethyl, 1-benzyloxyethyl, 1-phenoxypropyl,1-benzyloxypropyl, 1-adamantyloxyethyl, 1-adamantyloxypropyl,2-tetrahydrofuryl, 2-tetrahydro-2H-pyranyl,1-(2-cyclohexanecarbonyloxyethoxy)ethyl,1-(2-cyclohexanecarbonyloxyethoxy)propyl,1-[2-(1-adamantylcarbonyloxy)ethoxy]ethyl, and1-[2-(1-adamantylcarbonyloxy)ethoxy]propyl.

Illustrative examples of the tertiary alkyl group of formula (C2)include, but are not limited to, t-butyl, t-pentyl,1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl,1-adamantyl-1-methylethyl, 1-methyl-1-(2-norbornyl)ethyl,1-methyl-1-(tetrahydrofuran-2-yl)ethyl,1-methyl-1-(7-oxanorbornan-2-yl)ethyl, 1-methylcyclopentyl,1-ethylcyclopentyl, 1-propylcyclopentyl, 1-cyclopentylcyclopentyl,1-cyclohexylcyclopentyl, 1-(2-tetrahydrofuryl)cyclopentyl,1-(7-oxanorbornan-2-yl)cyclopentyl, 1-methylcyclohexyl,1-ethylcyclohexyl, 1-cyclopentylcyclohexyl, 1-cyclohexylcyclohexyl,2-methyl-2-norbornyl, 2-ethyl-2-norbornyl,8-methyl-8-tricyclo[5.2.1.0^(2,6)]decyl,8-ethyl-8-tricyclo[5.2.1.0^(2,6)]decyl,3-methyl-3-tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecyl,3-ethyl-3-tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecyl,2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-methyl-3-oxo-1-cyclohexyl,1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 5-hydroxy-2-methyl-2-adamantyl,and 5-hydroxy-2-ethyl-2-adamantyl.

In the base resin, at least 1 mol % of hydrogen atoms of hydroxyl groupsmay be substituted by acid labile groups of the following generalformula (C3a) or (C3b) for crosslinkage between molecules or within amolecule.

Herein, R²⁰⁷ and R²⁰⁸ each are hydrogen or a straight, branched orcyclic C₁-C₈ alkyl group, or R²⁰⁷ and R²⁰⁸, taken together, may form aring with the carbon atom to which they are attached, with the provisothat each of R²⁰⁷ and R²⁰⁸ is a straight or branched C₁-C₈ alkylenegroup when they form a ring. R²⁰⁹ is a straight, branched or cyclicC₁-C₁₀ alkylene group. Letter “a” is an integer of 1 to 7 and “b” is 0or an integer of 1 to 10. “A” is a (a+1)-valent aliphatic or alicyclicsaturated hydrocarbon group, aromatic hydrocarbon group or heterocyclicgroup of 1 to 50 carbon atoms, which may have an intervening hetero atomand in which the hydrogen atom attached to a carbon atom may bepartially replaced by a hydroxyl group, carboxyl group, carbonyl groupor fluorine atom. B is —CO—O—, —NHCO—O— or —NHCONH—.

Illustrative examples of the crosslinking acetal linkages represented byformulae (C3a) and (C3b) are given below as (C3-1) through (C3-8), butnot limited thereto.

Preferably the base resin has a weight average molecular weight (Mw) of2,000 to 100,000, as measured by gel permeation chromatography (GPC)versus polystyrene standards.

With Mw below 2,000, film formation and resolution may become poor. WithMw beyond 100,000, resolution may become poor or foreign matter maygenerate during pattern formation.

In the base resin, the proportion (on a molar basis) of acid labilegroup-containing monomer units relative to the other monomer units(constituent units) is typically in a range of 10 to 70%, preferably 20to 60%, in case intended for ArF excimer laser resist compositions; andtypically in a range of 10 to 50%, preferably 20 to 40%, in caseintended for KrF excimer laser resist compositions.

The monomer units other than the acid labile group-containing monomerunits are preferably monomer units containing polar groups such asalcohols, fluorinated alcohols, and ether, lactone, ester, acidanhydride, and carboxylic acid in the case of the base resins for ArFexcimer laser resist compositions. The base resins for KrF excimer laserresist compositions may comprise units of styrene, indene and4-acetoxystyrene in addition to 4-hydroxystyrene units having no acidlabile groups incorporated. The monomer units to be incorporated may beof one type or of two or more different types.

Component D

The quencher used as component (D) is preferably a compound capable ofsuppressing the rate of diffusion when the acid generated by thephotoacid generator diffuses within the resist film. The inclusion ofquencher facilitates to adjust the resist sensitivity and holds down therate of acid diffusion within the resist film, resulting in betterresolution. In addition, it suppresses changes in sensitivity followingexposure and reduces substrate and environment dependence, as well asimproving the exposure latitude and the pattern profile.

Suitable quenchers include primary, secondary, and tertiary aliphaticamines, mixed amines, aromatic amines, heterocyclic amines,nitrogen-containing compounds with carboxyl group, nitrogen-containingcompounds with sulfonyl group, nitrogen-containing compounds withhydroxyl group, nitrogen-containing compounds with hydroxyphenyl group,alcoholic nitrogen-containing compounds, amide derivatives, imidederivatives, carbamate derivatives, and ammonium salts.

Examples of suitable primary aliphatic amines include ammonia,methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine,isobutylamine, sec-butylamine, tert-butylamine, pentylamine,tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine,heptylamine, octylamine, nonylamine, decylamine, dodecylamine,cetylamine, methylenediamine, ethylenediamine, andtetraethylenepentamine. Examples of suitable secondary aliphatic aminesinclude dimethylamine, diethylamine, di-n-propylamine, diisopropylamine,di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine,dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine,dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine,N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, andN,N-dimethyltetraethylenepentamine. Examples of suitable tertiaryaliphatic amines include trimethylamine, triethylamine,tri-n-propylamine, triisopropylamine, tri-n-butylamine,triisobutylamine, tri-sec-butylamine, tripentylamine,tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, tridodecylamine,tricetylamine, N,N,N′,N′-tetramethylmethylenediamine,N,N,N′,N′-tetramethylethylenediamine, andN,N,N′,N′-tetramethyltetraethylenepentamine.

Examples of suitable mixed amines include dimethylethylamine,methylethylpropylamine, benzylamine, phenethylamine, andbenzyldimethylamine. Examples of suitable aromatic and heterocyclicamines include aniline derivatives (e.g., aniline, N-methylaniline,N-ethylaniline, N-propylaniline, N,N-dimethylaniline,N,N-bis(hydroxyethyl)aniline, 2-methylaniline, 3-methylaniline,4-methylaniline, ethylaniline, propylaniline, dimethylaniline,2,6-diisopropylaniline, trimethylaniline, 2-nitroaniline,3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline,3,5-dinitroaniline, and N,N-dimethyltoluidine), diphenyl(p-tolyl)amine,methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine,diaminonaphthalene, pyrrole derivatives (e.g., pyrrole, 2H-pyrrole,1-methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, andN-methylpyrrole), oxazole derivatives (e.g., oxazole and isooxazole),thiazole derivatives (e.g., thiazole and isothiazole), imidazolederivatives (e.g., imidazole, 4-methylimidazole, and4-methyl-2-phenylimidazole), pyrazole derivatives, furazane derivatives,pyrroline derivatives (e.g., pyrroline and 2-methyl-1-pyrroline),pyrrolidine derivatives (e.g., pyrrolidine, N-methylpyrrolidine,pyrrolidinone, and N-methylpyrrolidone), imidazoline derivatives,imidazolidine derivatives, pyridine derivatives (e.g., pyridine,methylpyridine, ethylpyridine, propylpyridine, butylpyridine,4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine,triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine,4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine,butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone,4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine,2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine),pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives,pyrazoline derivatives, pyrazolidine derivatives, piperidinederivatives, piperazine derivatives, morpholine derivatives, indolederivatives, isoindole derivatives, 1H-indazole derivatives, indolinederivatives, quinoline derivatives (e.g., quinoline and3-quinolinecarbonitrile), isoquinoline derivatives, cinnolinederivatives, quinazoline derivatives, quinoxaline derivatives,phthalazine derivatives, purine derivatives, pteridine derivatives,carbazole derivatives, phenanthridine derivatives, acridine derivatives,phenazine derivatives, 1,10-phenanthroline derivatives, adeninederivatives, adenosine derivatives, guanine derivatives, guanosinederivatives, uracil derivatives, and uridine derivatives.

Examples of suitable nitrogen-containing compounds with carboxyl groupinclude aminobenzoic acid, indolecarboxylic acid, and amino acidderivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid,glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine,methionine, phenylalanine, threonine, lysine,3-aminopyrazine-2-carboxylic acid, and methoxyalanine). Suitablenitrogen-containing compounds with sulfonyl group include3-pyridinesulfonic acid and pyridinium p-toluenesulfonate. Examples ofsuitable nitrogen-containing compounds with hydroxyl group,nitrogen-containing compounds with hydroxyphenyl group, and alcoholicnitrogen-containing compounds include 2-hydroxypyridine, aminocresol,2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine,diethanolamine, triethanolamine, N-ethyldiethanolamine,N,N-diethylethanolamine, triisopropanolamine, 2,2′-iminodiethanol,2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol,4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine,1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine,piperidine ethanol, 1-(2-hydroxyethyl)pyrrolidine,1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanediol,3-pyrrolidino-1,2-propanediol, 8-hydroxyjulolidine, 3-quinuclidinol,3-tropanol, 1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol,N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide.

Examples of suitable amide derivatives include formamide,N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide,N,N-dimethylacetamide, propionamide, and benzamide. Suitable imidederivatives include phthalimide, succinimide, and maleimide. Suitablecarbamate derivatives includeN-tert-butoxycarbonyl-N,N-dicyclohexylamine,N-tert-butoxycarbonylbenzimidazole, and oxazolidinone. Suitable ammoniumsalts include pyridinium p-toluenesulfonate, triethylammoniump-toluenesulfonate, trioctylammonium p-toluenesulfonate,triethylammonium 2,4,6-triisopropylbenzenesulfonate, trioctylammonium2,4,6-triisopropylbenzenesulfonate, triethylammonium camphorsulfonate,trioctylammonium camphorsulfonate, tetramethylammonium hydroxide,tetraethylammonium hydroxide, tetrabutylammonium hydroxide,benzyltrimethylammonium hydroxide, tetramethylammoniump-toluenesulfonate, tetrabutylammonium p-toluenesulfonate,benzyltrimethylammonium p-toluenesulfonate, tetramethylammoniumcamphorsulfonate, tetrabutylammonium camphorsulfonate,benzyltrimethylammonium camphorsulfonate, tetramethylammonium2,4,6-triisopropylbenzenesulfonate, tetrabutylammonium2,4,6-triisopropylbenzenesulfonate, benzyltrimethylammonium2,4,6-triisopropylbenzenesulfonate, tetramethylammonium acetate,tetrabutylammonium acetate, benzyltrimethylammonium acetate,tetramethylammonium benzoate, tetrabutylammonium benzoate, andbenzyltrimethylammonium benzoate.

In addition, amine compounds of the following general formula (Am-1) mayalso be included alone or in admixture.N(Rx)_(k)(Ry)_(3-k)  (Am-1)In the formula, k is equal to 1, 2 or 3. The side chain Rx isindependently selected from groups of the following general formulas(Rx-1) to (Rx-3). The side chain Ry is independently hydrogen or astraight, branched or cyclic C₁-C₂₀ alkyl group in which some or allhydrogen atoms may be substituted by fluorine atoms and which maycontain an ether or hydroxyl group. Two or three Rx may bond together toform a ring.

In the formulas, R³⁰¹, R³⁰³ and R³⁰⁶ are independently straight orbranched C₁-C₄ alkylene groups; R³⁰² and R³⁰⁵ are independently hydrogenor straight, branched or cyclic C₁-C₂₀ alkyl groups in which some or allhydrogen atoms may be substituted by fluorine atoms and which maycontain at least one hydroxyl group, ether group, ester group or lactonering; R³⁰⁴ is a single bond or a straight or branched C₁-C₄ alkylenegroup; R³⁰⁷ is a straight, branched or cyclic C₁-C₂₀ alkyl group inwhich some or all hydrogen atoms may be substituted by fluorine atomsand which may contain at least one hydroxyl group, ether group, estergroup or lactone ring.

Illustrative examples of the compounds of formula (Am-1) include, butare not limited to, tris(2-methoxymethoxyethyl)amine,tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine,4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane,4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane,1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane,1-aza-12-crown-4,1-aza-15-crown-5,1-aza-18-crown-6,tris(2-formyloxyethyl)amine, tris(2-acetoxyethyl)amine,tris(2-propionyloxyethyl)amine, tris(2-butyryloxyethyl)amine,tris(2-isobutyryloxyethyl)amine, tris(2-valeryloxyethyl)amine,tris(2-pivaloyloxyethyl)amine,N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine,tris(2-methoxycarbonyloxyethyl)amine,tris(2-tert-butoxycarbonyloxyethyl)amine,tris[2-(2-oxopropoxy)ethyl]amine,tris[2-(methoxycarbonylmethyl)oxyethyl]amine,tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine,tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine,tris(2-methoxycarbonylethyl)amine, tris(2-ethoxycarbonylethyl)amine,N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylamine,N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylamine,N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine,N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)ethylamine,N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)ethylamine,N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine,N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-butylbis[2-(methoxycarbonyl)ethyl]amine,N-butylbis[2-(2-methoxyethoxycarbonyl)ethyl]amine,N-methylbis(2-acetoxyethyl)amine, N-ethylbis(2-acetoxyethyl)amine,N-methylbis(2-pivaloyloxyethyl)amine,N-ethylbis[2-(methoxycarbonyloxy)ethyl]amine,N-ethylbis[2-(tert-butoxycarbonyloxy)ethyl]amine,tris(methoxycarbonylmethyl)amine, tris(ethoxycarbonylmethyl)amine,N-butylbis(methoxycarbonylmethyl)amine,N-hexylbis(methoxycarbonylmethyl)amine, andβ-(diethylamino)-δ-valerolactone.

Also useful are one or more of cyclic structure-bearing amine compoundshaving the following general formula (Am-2).

Herein Rx is as defined above, and R³⁰⁸ is a straight or branched C₂-C₂₀alkylene group in which some or all hydrogen atoms may be substituted byfluorine atoms and which may contain one or more carbonyl, ether, esteror sulfide groups.

Illustrative examples of the cyclic structure-bearing amine compoundshaving formula (Am-2) include 1-[2-(methoxymethoxy)ethyl]pyrrolidine,1-[2-(methoxymethoxy)ethyl]piperidine,4-[2-(methoxymethoxy)ethyl]morpholine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine,4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine,2-[2-(2-methoxyethoxy)ethoxy]ethylmorpholine,2-[2-(2-butoxyethoxy)ethoxy]ethylmorpholine,2-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}ethylmorpholine,2-{2-[2-(2-butoxyethoxy)ethoxy]ethoxy}ethylmorpholine,2-(1-pyrrolidinyl)ethyl acetate, 2-piperidinoethyl acetate,2-morpholinoethyl acetate, 2-(1-pyrrolidinyl)ethyl formate,2-piperidinoethyl propionate, 2-morpholinoethyl acetoxyacetate,2-(1-pyrrolidinyl)ethyl methoxyacetate,4-[2-(methoxycarbonyloxy)ethyl]morpholine,1-[2-(t-butoxycarbonyloxy)ethyl]piperidine,4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine, methyl3-(1-pyrrolidinyl)propionate, methyl 3-piperidinopropionate, methyl3-morpholinopropionate, methyl 3-(thiomorpholino)propionate, methyl2-methyl-3-(1-pyrrolidinyl)propionate, ethyl 3-morpholinopropionate,methoxycarbonylmethyl 3-piperidinopropionate, 2-hydroxyethyl3-(1-pyrrolidinyl)propionate, 2-acetoxyethyl 3-morpholinopropionate,2-oxotetrahydrofuran-3-yl 3-(1-pyrrolidinyl)propionate,tetrahydrofurfuryl 3-morpholinopropionate, glycidyl3-piperidinopropionate, 2-methoxyethyl 3-morpholinopropionate,2-(2-methoxyethoxy)ethyl 3-(1-pyrrolidinyl)propionate, butyl3-morpholinopropionate, cyclohexyl 3-piperidinopropionate,α-(1-pyrrolidinyl)methyl-γ-butyrolactone, β-piperidino-γ-butyrolactone,β-morpholino-δ-valerolactone, methyl 1-pyrrolidinylacetate, methylpiperidinoacetate, methyl morpholinoacetate, methylthiomorpholinoacetate, ethyl 1-pyrrolidinylacetate, 2-methoxyethylmorpholinoacetate, 2-morpholinoethyl 2-methoxyacetate, 2-morpholinoethyl2-(2-methoxyethoxy)acetate, 2-morpholinoethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-morpholinoethyl hexanoate,2-morpholinoethyl octanoate, 2-morpholinoethyl decanoate,2-morpholinoethyl laurate, 2-morpholinoethyl myristate,2-morpholinoethyl palmitate, 2-morpholinoethyl stearate,2-morpholinoethyl cyclohexanecarboxylate, and 2-morpholinoethyladamantanecarboxylate.

Also, one or more of cyano-bearing amine compounds having the followinggeneral formulae (Am-3) to (Am-6) may be added.

Herein, Rx, R³⁰⁸ and k are as defined in formula (Am-1), and R³⁰⁹ andR³¹⁰ each are independently a straight or branched C₁-C₄ alkylene group.

Illustrative examples of the cyano-bearing amine compounds havingformulae (Am-3) to (Am-6) include 3-(diethylamino)propiononitrile,N,N-bis(2-hydroxyethyl)-3-aminopropiononitrile,N,N-bis(2-acetoxyethyl)-3-aminopropiononitrile,N,N-bis(2-formyloxyethyl)-3-aminopropiononitrile,N,N-bis(2-methoxyethyl)-3-aminopropiononitrile,N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile, methylN-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropionate, methylN-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropionate, methylN-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropionate,N-(2-cyanoethyl)-N-ethyl-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropiononitrile,N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-formyloxyethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(3-hydroxy-1-propyl)-3-aminopropiononitrile,N-(3-acetoxy-1-propyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(3-formyloxy-1-propyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-tetrahydrofurfuryl-3-aminopropiononitrile,N,N-bis(2-cyanoethyl)-3-aminopropiononitrile, diethylaminoacetonitrile,N,N-bis(2-hydroxyethyl)aminoacetonitrile,N,N-bis(2-acetoxyethyl)aminoacetonitrile,N,N-bis(2-formyloxyethyl)aminoacetonitrile,N,N-bis(2-methoxyethyl)aminoacetonitrile,N,N-bis[2-(methoxymethoxy)ethyl]aminoacetonitrile, methylN-cyanomethyl-N-(2-methoxyethyl)-3-aminopropionate, methylN-cyanomethyl-N-(2-hydroxyethyl)-3-aminopropionate, methylN-(2-acetoxyethyl)-N-cyanomethyl-3-aminopropionate,N-cyanomethyl-N-(2-hydroxyethyl)aminoacetonitrile,N-(2-acetoxyethyl)-N-(cyanomethyl)aminoacetonitrile,N-cyanomethyl-N-(2-formyloxyethyl)aminoacetonitrile,N-cyanomethyl-N-(2-methoxyethyl)aminoacetonitrile,N-cyanomethyl-N-(2-(methoxymethoxy)ethyl)aminoacetonitrile,N-cyanomethyl-N-(3-hydroxy-1-propyl)aminoacetonitrile,N-(3-acetoxy-1-propyl)-N-(cyanomethyl)aminoacetonitrile,N-cyanomethyl-N-(3-formyloxy-1-propyl)aminoacetonitrile,N,N-bis(cyanomethyl)aminoacetonitrile, 1-pyrrolidinepropiononitrile,1-piperidinepropiononitrile, 4-morpholinepropiononitrile,1-pyrrolidineacetonitrile, 1-piperidineacetonitrile,4-morpholineacetonitrile, cyanomethyl 3-diethylaminopropionate,cyanomethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-acetoxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-formyloxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-methoxyethyl)-3-aminopropionate, cyanomethylN,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, 2-cyanoethyl3-diethylaminopropionate, 2-cyanoethylN,N-bis(2-hydroxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-acetoxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-formyloxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-methoxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, cyanomethyl1-pyrrolidinepropionate, cyanomethyl 1-piperidinepropionate, cyanomethyl4-morpholinepropionate, 2-cyanoethyl 1-pyrrolidinepropionate,2-cyanoethyl 1-piperidinepropionate, and 2-cyanoethyl4-morpholinepropionate.

Also included are amine compounds having an imidazole structure and apolar functional group, represented by the general formula (Am-7).

Herein, R³¹¹ is a straight, branched or cyclic C₂-C₂₀ alkyl group inwhich some or all hydrogen atoms may be substituted by fluorine atomsand which has one or more polar functional groups. The polar functionalgroup is selected from among hydroxyl, carbonyl, ester, ether, sulfide,carbonate, cyano and acetal groups and mixtures thereof. R³¹², R³¹³ andR³¹⁴ are each independently a hydrogen atom, a straight, branched orcyclic C₁-C₁₀ alkyl group, aryl group or aralkyl group.

Also included are amine compounds having a benzimidazole structure and apolar functional group, represented by the general formula (Am-8).

Herein, R³¹⁵ is a straight, branched or cyclic C₁-C₂₀ alkyl group inwhich some or all hydrogen atoms may be substituted by fluorine atomsand which has one or more polar functional groups. The alkyl groupcontains as the polar functional group at least one group selected fromamong ester, acetal and cyano groups, and may additionally contain atleast one group selected from among hydroxyl, carbonyl, ether, sulfideand carbonate groups. R³¹⁶ is a hydrogen atom, a straight, branched orcyclic C₁-C₁₀ alkyl group, aryl group or aralkyl group.

Further included are heterocyclic nitrogen-containing compounds having apolar functional group, represented by the general formulae (Am-9) and(Am-10).

Herein, J is a nitrogen atom or ≡C—R³²³. K is a nitrogen atom or≡C—R³²⁴. R³¹⁷ is a straight, branched or cyclic C₂-C₂₀ alkyl group inwhich some or all hydrogen atoms may be substituted by fluorine atomsand which has one or more polar functional groups, the polar functionalgroup being selected from among hydroxyl, carbonyl, ester, ether,sulfide, carbonate, cyano and acetal groups and mixtures thereof. R³¹⁸,R³¹⁹, R³²⁰ and R³²¹ are each independently a hydrogen atom, a straight,branched or cyclic C₁-C₁₀ alkyl group or aryl group, or a pair of R³¹⁸and R³¹⁹ and a pair of R³²⁰ and R³²¹, taken together, may form abenzene, naphthalene or pyridine ring. R³²² is a hydrogen atom, astraight, branched or cyclic C₁-C₁₀ alkyl group or aryl group. R³²³ andR³²⁴ each are a hydrogen atom, a straight, branched or cyclic C₁-C₁₀alkyl group or aryl group, or a pair of R³²³ and R³²⁴, taken together,may form a benzene or naphthalene ring.

Also included are amine compounds having an aromatic carboxylic acidester structure, represented by the general formulae (Am-11) to (Am-14).

Herein R³²⁵ is a C₆-C₂₀ aryl group or C₄-C₂₀ hetero-aromatic group, inwhich some or all hydrogen atoms may be replaced by halogen atoms,straight, branched or cyclic C₁-C₂₀ alkyl groups, C₆-C₂₀ aryl groups,C₇-C₂₀ aralkyl groups, C₁-C₁₀ alkoxy groups, C₁-C₁₀ acyloxy groups orC₁-C₁₀ alkylthio groups. R³²⁶ is CO₂R³²⁷, OR³²⁸ or cyano group. R³²⁷ isa C₁-C₁₀ alkyl group, in which some methylene groups may be replaced byoxygen atoms. R³²⁸ is a C₁-C₁₀ alkyl or acyl group, in which somemethylene groups may be replaced by oxygen atoms. R³²⁹ is a single bond,methylene, ethylene, sulfur atom or —O(CH₂CH₂O)_(h)— group wherein h is0, 1, 2, 3 or 4. R³³⁰ is hydrogen, methyl, ethyl or phenyl. T is anitrogen atom or CR³³¹. U is a nitrogen atom or CR³³². V is a nitrogenatom or CR³³³. R³³¹, R³³² and R³³³ are each independently hydrogen,methyl or phenyl. Alternatively, a pair of R³³¹ and R³³² or a pair ofR³³² and R³³³ may bond together to form a C₆-C₂₀ aromatic ring or C₂-C₂₀hetero-aromatic ring.

Further included are amine compounds of 7-oxanorbornane-2-carboxylicester structure, represented by the general formula (Am-15).

Herein R³³⁴ is hydrogen or a straight, branched or cyclic C₁-C₁₀ alkylgroup. R³³⁵ and R³³⁶ are each independently a C₁-C₂₀ alkyl group, C₆-C₂₀aryl group or C₇-C₂₀ aralkyl group, which may contain one or more polarfunctional groups selected from among ether, carbonyl, ester, alcohol,sulfide, nitrile, amine, imine, and amide and in which some hydrogenatoms may be replaced by halogen atoms. R³³⁵ and R³³⁶, taken together,may form a heterocyclic or hetero-aromatic ring of 2 to 20 carbon atoms.

The quenchers may be used alone or in admixture of two or more. Thequencher is preferably formulated in an amount of 0.001 to 2 parts, andespecially 0.01 to 1 part by weight, per 100 parts by weight of the baseresin. Less than 0.001 phr of the quencher may achieve no additioneffect whereas more than 2 phr may lead to too low a sensitivity.

Component E

In one preferred embodiment, the resist composition further contains (E)an auxiliary photoacid generator other than component (A). It may be anycompound capable of generating an acid upon exposure to high-energyradiation such as UV, deep UV, electron beam, EUV, x-ray, excimer laserbeam, gamma-ray or synchrotron radiation. Suitable auxiliary photoacidgenerators include sulfonium salts, iodonium salts,sulfonyldiazomethane, N-sulfonyloxydicarboxylmide, O-arylsulfonyloximeand O-alkylsulfonyloxime photoacid generators. Exemplary auxiliaryphotoacid generators are given below while they may be used alone or inadmixture of two or more.

Sulfonium salts are salts of sulfonium cations with sulfonates,bis(substituted alkylsulfonyl)imides and tris(substitutedalkylsulfonyl)methides. Exemplary sulfonium cations includetriphenylsulfonium, (4-tert-butoxyphenyl)diphenylsulfonium,bis(4-tert-butoxyphenyl)phenylsulfonium,tris(4-tert-butoxyphenyl)sulfonium,(3-tert-butoxyphenyl)diphenylsulfonium,bis(3-tert-butoxyphenyl)phenylsulfonium,tris(3-tert-butoxyphenyl)sulfonium,(3,4-di-tert-butoxyphenyl)diphenylsulfonium,bis(3,4-di-tert-butoxyphenyl)phenylsulfonium,tris(3,4-di-tert-butoxyphenyl)sulfonium,diphenyl(4-thiophenoxyphenyl)sulfonium,(4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium,tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium,(4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium,tris(4-dimethylaminophenyl)sulfonium, 4-methylphenyldiphenylsulfonium,4-tert-butylphenylsulfonium, bis(4-methylphenyl)phenylsulfonium,bis(4-tert-butylphenyl)phenylsulfonium, tris(4-methylphenyl)sulfonium,tris(4-tert-butylphenyl)sulfonium, tris(phenylmethyl)sulfonium,2-naphthyldiphenylsulfonium, dimethyl(2-naphthyl)sulfonium,4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium,trimethylsulfonium, 2-oxocyclohexylcyclohexylmethylsulfonium,trinaphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium,dimethylphenylsulfonium, 2-oxopropylthiacyclopentanium,2-oxobutylthiacyclopentanium, 2-oxo-3,3-dimethylbutylthiacyclopentanium,2-oxo-2-phenylethylthiacyclopentanium,4-n-butoxynaphthyl-1-thiacyclopentanium, and2-n-butoxynaphthyl-1-thiacyclopentanium. Exemplary sulfonates includetrifluoromethanesulfonate, pentafluoroethanesulfonate,heptafluoropropanesulfonate, nonafluorobutanesulfonate,tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate,4-fluorobenzenesulfonate, mesitylenesulfonate,2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate,4-(p-toluenesulfonyloxy)benzenesulfonate,6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthylethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate,2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate. Exemplarybis(substituted alkylsulfonyl)imides includebis(trifluoromethylsulfonyl)imide, bis(pentafluoroethylsulfonyl)imide,bis(heptafluoropropylsulfonyl)imide, andperfluoro(1,3-propylenebissulfonyl)imide.

A typical tris(substituted alkylsulfonyl)methide istris(trifluoromethylsulfonyl)methide. Sulfonium salts based oncombination of the foregoing examples are included.

Iodonium salts are salts of iodonium cations with sulfonates,bis(substituted alkylsulfonyl)imides and tris(substitutedalkylsulfonyl)methides. Exemplary iodonium cations includediphenyliodonium, bis(4-tert-butylphenyl)iodonium,4-tert-butoxyphenylphenyliodonium, and 4-methoxyphenylphenyliodonium.Exemplary sulfonates include trifluoromethanesulfonate,pentafluoroethanesulfonate, nonafluorobutanesulfonate,tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate,4-fluorobenzenesulfonate, mesitylenesulfonate,2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate,4-(p-toluenesulfonyloxy)benzenesulfonate,6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthylethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate,2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate. Exemplarybis(substituted alkylsulfonyl)imides includebis(trifluoromethylsulfonyl)imide, bis(pentafluoroethylsulfonyl)imide,bis(heptafluoropropylsulfonyl)imide, andperfluoro(1,3-propylenebissulfonyl)imide. A typical tris(substitutedalkylsulfonyl)methide is tris(trifluoromethylsulfonyl)methide. Iodoniumsalts based on combination of the foregoing examples are included.

Exemplary sulfonyldiazomethane compounds include bissulfonyldiazomethanecompounds and sulfonylcarbonyldiazomethane compounds such asbis(ethylsulfonyl)diazomethane, bis(1-methylpropylsulfonyl)diazomethane,bis(2-methylpropylsulfonyl)diazomethane,bis(1,1-dimethylethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(perfluoroisopropylsulfonyl)diazomethane,bis(phenylsulfonyl)diazomethane,bis(4-methylphenylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(4-acetyloxyphenylsulfonyl)diazomethane,bis(4-(methanesulfonyloxy)phenylsulfonyl)diazomethane,bis(4-(p-toluenesulfonyloxy)phenylsulfonyl)diazomethane,bis(4-(n-hexyloxy)phenylsulfonyl)diazomethane,bis(2-methyl-4-(n-hexyloxy)phenylsulfonyl)diazomethane,bis(2,5-dimethyl-4-(n-hexyloxy)phenylsulfonyl)diazomethane,bis(3,5-dimethyl-4-(n-hexyloxy)phenylsulfonyl)diazomethane,bis(2-methyl-5-isopropyl-4-(n-hexyloxy)phenylsulfonyl)diazomethane,bis(2-naphthylsulfonyl)diazomethane,4-methylphenylsulfonylbenzoyldiazomethane,tert-butylcarbonyl-4-methylphenylsulfonyldiazomethane,2-naphthylsulfonylbenzoyldiazomethane,4-methylphenylsulfonyl-2-naphthoyldiazomethane,methylsulfonylbenzoyldiazomethane, andtert-butoxycarbonyl-4-methylphenylsulfonyldiazomethane.

N-sulfonyloxyimide photoacid generators include combinations of imideskeletons with sulfonates. Exemplary imide skeletons are succinimide,naphthalenedicarboximide, phthalimide, cyclohexyldicarboximide,5-norbornene-2,3-dicarboximide, and7-oxabicyclo[2.2.1]-5-heptene-2,3-dicarboximide. Exemplary sulfonatesinclude trifluoromethanesulfonate, pentafluoroethanesulfonate,heptafluoropropanesulfonate, nonafluorobutanesulfonate,tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate,4-fluorobenzenesulfonate, mesitylenesulfonate,2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate,4-(p-toluenesulfonyloxy)benzenesulfonate,6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthylethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate,2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Benzoinsulfonate photoacid generators include benzoin tosylate, benzoinmesylate, and benzoin butanesulfonate.

Pyrogallol trisulfonate photoacid generators include pyrogallol,phloroglucin, catechol, resorcinol, and hydroquinone, in which all thehydroxyl groups are substituted by trifluoromethanesulfonate,pentafluoroethanesulfonate, heptafluoropropanesulfonate,nonafluorobutanesulfonate, tridecafluorohexanesulfonate,perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate,4-(p-toluenesulfonyloxy)benzenesulfonate,6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthylethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate,2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Nitrobenzyl sulfonate photoacid generators include 2,4-dinitrobenzylsulfonate, 2-nitrobenzyl sulfonate, and 2,6-dinitrobenzyl sulfonate,with exemplary sulfonates including trifluoromethanesulfonate,pentafluoroethanesulfonate, heptafluoropropanesulfonate,nonafluorobutanesulfonate, tridecafluorohexanesulfonate,perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate,4-(p-toluenesulfonyloxy)benzenesulfonate,6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, camphorsulfonate,octanesulfonate, dodecylbenzenesulfonate, butanesulfonate,methanesulfonate, 1,1-difluoro-2-naphthylethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate,2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate. Also usefulare analogous nitrobenzyl sulfonate compounds in which the nitro groupon the benzyl side is substituted by a trifluoromethyl group.

Sulfone photoacid generators include bis(phenylsulfonyl)methane,bis(4-methylphenylsulfonyl)methane, bis(2-naphthylsulfonyl)methane,2,2-bis(phenylsulfonyl)propane, 2,2-bis(4-methylphenylsulfonyl)propane,2,2-bis(2-naphthylsulfonyl)propane,2-methyl-2-(p-toluenesulfonyl)propiophenone,2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane, and2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one.

Suitable O-arylsulfonyloxime compounds and O-alkylsulfonyloximecompounds (oxime sulfonates) include photoacid generators in the form ofglyoxime derivatives, oxime sulfonates with a long conjugated systemseparated by thiophene or cyclohexadiene, oxime sulfonates having anelectron withdrawing group such as trifluoromethyl incorporated forincreased stability, oxime sulfonates using phenylacetonitrile orsubstituted acetonitrile derivatives, and bisoxime sulfonates.

Photoacid generators in the form of glyoxime derivatives includebis-O-(p-toluenesulfonyl)-α-dimethylglyoxime,bis-O-(p-toluenesulfonyl)-α-diphenylglyoxime,bis-O-(p-toluenesulfonyl)-α-dicyclohexylglyoxime,bis-O-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,bis-O-(n-butanesulfonyl)-α-dimethylglyoxime,bis-O-(n-butanesulfonyl)-α-diphenylglyoxime,bis-O-(n-butanesulfonyl)-α-dicyclohexylglyoxime,bis-O-(methanesulfonyl)-α-dimethylglyoxime,bis-O-(trifluoromethanesulfonyl)-α-dimethylglyoxime,bis-O-(2,2,2-trifluoroethanesulfonyl)-α-dimethylglyoxime,bis-O-(10-camphorsulfonyl)-α-dimethylglyoxime,bis-O-(benzenesulfonyl)-α-dimethylglyoxime,bis-O-(p-fluorobenzenesulfonyl)-α-dimethylglyoxime,bis-O-(p-trifluoromethylbenzenesulfonyl)-α-dimethylglyoxime,bis-O-(xylenesulfonyl)-α-dimethylglyoxime,bis-O-(trifluoromethanesulfonyl)-nioxime,bis-O-(2,2,2-trifluoroethanesulfonyl)-nioxime,bis-O-(10-camphorsulfonyl)-nioxime, bis-O-(benzenesulfonyl)-nioxime,bis-O-(4-fluorobenzenesulfonyl)-nioxime,bis-O-(4-trifluoromethylbenzenesulfonyl)-nioxime, andbis-O-(xylenesulfonyl)-nioxime. Also included are compounds of theforegoing skeleton having substituted thereon2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Photoacid generators in the form of oxime sulfonates with a longconjugated system separated by thiophene or cyclohexadiene include(5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,(5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,(5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,(5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,(5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,(5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,(5-(4-(p-toluenesulfonyloxy)benzenesulfonyl)oxyimino-5H-thiophen-2-ylidenephenylacetonitrile, and(5-(2,5-bis(p-toluenesulfonyloxy)benzenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile.

Also included are modified forms of the foregoing compounds havingsubstituted on their skeleton2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Suitable oxime sulfonates having an electron withdrawing group such astrifluoromethyl incorporated for increased stability include2,2,2-trifluoro-1-phenyl-ethanone O-(methylsulfonyl)oxime,2,2,2-trifluoro-1-phenyl-ethanone O-(10-camphorsulfonyl)oxime,2,2,2-trifluoro-1-phenylethanone O-(4-methoxybenzenesulfonyl)oxime,2,2,2-trifluoro-1-phenylethanone O-(1-naphthylsulfonyl)oxime,2,2,2-trifluoro-1-phenylethanone O-(2-naphthylsulfonyl)oxime,2,2,2-trifluoro-1-phenylethanone O-(2,4,6-trimethylphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methylphenyl)ethanone O-(10-camphorsulfonyl)oxime,2,2,2-trifluoro-1-(4-methylphenyl)ethanone O-(methylsulfonyl)oxime,2,2,2-trifluoro-1-(2-methylphenyl)ethanone O-(10-camphorsulfonyl)oxime,2,2,2-trifluoro-1-(2,4-dimethylphenyl)ethanoneO-(10-camphorsulfonyl)oxime,2,2,2-trifluoro-1-(2,4-dimethylphenyl)ethanoneO-(1-naphthylsulfonyl)oxime,2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneO-(2-naphthylsulfonyl)oxime,2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanoneO-(10-camphorsulfonyl)oxime,2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanoneO-(1-naphthylsulfonyl)oxime,2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanoneO-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylthiophenyl)-ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(3,4-dimethoxyphenyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanoneO-(4-methylphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methoxyphenyl)ethanoneO-(4-methoxyphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methoxyphenyl)ethanoneO-(4-dodecylphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methoxyphenyl)ethanone O-(octylsulfonyl)oxime,2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanoneO-(4-methoxyphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanoneO-(4-dodecylphenylsulfonyl)oxime,2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanone O-(octylsulfonyl)oxime,2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanoneO-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-methylphenyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylphenyl)ethanoneO-(phenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-chlorophenyl)ethanoneO-(phenylsulfonyl)oxime, 2,2,3,3,4,4,4-heptafluoro-1-phenylbutanoneO-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(1-naphthyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-naphthyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzylphenyl)ethanoneO-(methylsulfonyl)oxime,2,2,2-trifluoro-1-(4-(phenyl-1,4-dioxa-but-1-yl)phenyl)ethanoneO-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(1-naphthyl)ethanoneO-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-naphthyl)ethanoneO-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzylphenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methylsulfonylphenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methylsulfonyloxyphenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methylcarbonyloxyphenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(6H,7H-5,8-dioxonaphth-2-yl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methoxycarbonylmethoxyphenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-methoxycarbonyl)-(4-amino-1-oxa-pent-1-yl)phenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(3,5-dimethyl-4-ethoxyphenyl)ethanoneO-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzyloxyphenyl)ethanoneO-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-thiophenyl)ethanoneO-(propylsulfonate)oxime, and2,2,2-trifluoro-1-(1-dioxathiophen-2-yl)ethanoneO-(propylsulfonate)oxime;2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(trifluoromethanesulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanoneO-(trifluoromethanesulfonyl)oxime,2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(1-propanesulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanoneO-(propylsulfonyl)oxime,2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(1-butanesulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanoneO-(butylsulfonyl)oxime,2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(4-(4-methylphenylsulfonyloxy)phenylsulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanoneO-(4-(4-methylphenylsulfonyloxy)phenylsulfonyl)oxime, and2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(2,5-bis(4-methylphenylsulfonyloxy)benzenesulfonyloxy)phenylsulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanoneO-(2,5-bis(4-methylphenylsulfonyloxy)benzenesulfonyloxy)phenylsulfonyl)oxime.Also included are modified forms of the foregoing compounds havingsubstituted on their skeleton2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Also included are oxime sulfonates having the formula (Ox-1):

wherein R⁴⁰¹ is a substituted or unsubstituted C₁-C₁₀ haloalkylsulfonylor halobenzenesulfonyl group, R⁴⁰² is a C₁-C₁₁ haloalkyl group, andAr⁴⁰¹ is substituted or unsubstituted aromatic or hetero-aromatic group.

Examples include2-[2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl]fluorene,2-[2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl]fluorene,2-[2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl]fluorene,2-[2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl]-4-biphenyl,2-[2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl]-4-biphenyl,and2-[2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl]-4-biphenyl.Also included are modified forms of the foregoing compounds havingsubstituted on their skeleton2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Suitable oxime sulfonate generators using substituted acetonitrilederivatives include α-(p-toluenesulfonyloxyimino)-phenylacetonitrile,α-(p-chlorobenzenesulfonyloxyimino)-phenylacetonitrile,α-(4-nitrobenzenesulfonyloxyimino)-phenylacetonitrile,α-(4-nitro-2-trifluoromethylbenzenesulfonyloxyimino)phenylacetonitrile,α-(benzenesulfonyloxyimino)-4-chlorophenylacetonitrile,α-(benzenesulfonyloxyimino)-2,4-dichlorophenylacetonitrile,α-(benzenesulfonyloxyimino)-2,6-dichlorophenylacetonitrile,α-(benzenesulfonyloxyimino)-4-methoxyphenylacetonitrile,α-(2-chlorobenzenesulfonyloxyimino)-4-methoxyphenylacetonitrile,α-(benzenesulfonyloxyimino)-2-thienylacetonitrile,α-(4-dodecylbenzenesulfonyloxyimino)-phenylacetonitrile,α-[(4-toluenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile,α-[(dodecylbenzenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile,α-(tosyloxyimino)-3-thienylacetonitrile,α-(methylsulfonyloxyimino)-1-cyclopentenylacetonitrile,α-(ethylsulfonyloxyimino)-1-cyclopentenylacetonitrile,α-(isopropylsulfonyloxyimino)-1-cyclopentenylacetonitrile,α-(n-butylsulfonyloxyimino)-1-cyclopentenylacetonitrile,α-(ethylsulfonyloxyimino)-1-cyclohexenylacetonitrile,α-(isopropylsulfonyloxyimino)-1-cyclohexenylacetonitrile, andα-(n-butylsulfonyloxyimino)-1-cyclohexenylacetonitrile. Also includedare modified forms of the foregoing compounds having substituted ontheir skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

Suitable bisoxime sulfonates includebis(α-(p-toluenesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(benzenesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(methanesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(butanesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(10-camphorsulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(trifluoromethanesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(4-methoxybenzenesulfonyloxy)imino)-p-phenylenediacetonitrile,bis(α-(4-toluenesulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(benzenesulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(methanesulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(butanesulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(10-camphorsulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(trifluoromethanesulfonyloxy)imino)-m-phenylenediacetonitrile,bis(α-(4-methoxybenzenesulfonyloxy)imino)-m-phenylenediacetonitrile,etc.

Also included are modified forms of the foregoing compounds havingsubstituted on their skeleton2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate,2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate,2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate,1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate,1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate,1,1-difluoro-2-tosyloxyethanesulfonate,adamantanemethoxycarbonyldifluoromethanesulfonate,1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,methoxycarbonyldifluoromethanesulfonate,1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate,and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

When the photoacid generator (E) is added to the KrF excimer laserresist composition, preference is given to sulfonium salts,bissulfonyldiazomethanes, N-sulfonyloxyimides and oxime-O-sulfonates.Illustrative preferred photoacid generators include triphenylsulfoniump-toluenesulfonate, triphenylsulfonium camphorsulfonate,triphenylsulfonium pentafluorobenzenesulfonate, triphenylsulfoniumnonafluorobutanesulfonate, triphenylsulfonium4-(p-toluenesulfonyloxy)benzenesulfonate, triphenylsulfonium2,4,6-triisopropylbenzenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniump-toluenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniumcamphorsulfonate, 4-tert-butoxyphenyldiphenylsulfonium4-(p-toluenesulfonyloxy)benzenesulfonate,4-tert-butylphenyldiphenylsulfonium camphorsulfonate,tris(4-methylphenyl)sulfonium camphorsulfonate,tris(4-tert-butylphenyl)sulfonium camphorsulfonate,bis(tert-butylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(4-n-hexyloxyphenylsulfonyl)diazomethane,bis(2-methyl-4-n-hexylbxyphenylsulfonyl)diazomethane,bis(2,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane,bis(3,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane,bis(2-methyl-5-isopropyl-4-n-hexyloxy)phenylsulfonyldiazomethane,bis(4-tert-butylphenylsulfonyl)diazomethane,N-camphorsulfonyloxy-5-norbornene-2,3-dicarboxylic acid imide,N-p-toluenesulfonyloxy-5-norbornene-2,3-dicarboxylic acid imide,(5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,and(5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile.

When the photoacid generator (E) is added to the ArF laser resistcomposition, preference is given to sulfonium salts andoxime-O-sulfonates. Illustrative preferred photoacid generators includetriphenylsulfonium trifluoromethanesulfonate, triphenylsulfoniumpentafluoroethanesulfonate, triphenylsulfoniumheptafluoropropanesulfonate, triphenylsulfoniumnonafluorobutanesulfonate, triphenylsulfoniumtridecafluorohexanesulfonate, triphenylsulfoniumheptadecafluorooctanesulfonate, triphenylsulfoniumperfluoro(4-ethylcyclohexane)sulfonate, 4-methylphenyldiphenylsulfoniumnonafluorobutanesulfonate, 2-oxo-2-phenylethylthiacyclopentaniumnonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfoniumnonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfoniumperfluoro(4-ethylcyclohexane)sulfonate,4-tert-butylphenyldiphenylsulfonium heptafluorooctanesulfonate,triphenylsulfonium 1,1-difluoro-2-naphthylethanesulfonate,triphenylsulfonium1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,triphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate,triphenylsulfonium2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate,triphenylsulfonium1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,triphenylsulfonium methoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfonium2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfoniumadamantanemethoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfonium1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfoniummethoxycarbonyldifluoromethanesulfonate,2-oxo-2-phenylethylthiacyclopentanium2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-oxo-2-phenylethylthiacyclopentanium2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium perfluoro(1,3-propylenebissulfonyl)imide,triphenylsulfonium bis(pentafluoroethylsulfonyl)imide,2-(2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl)fluorene,2-(2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl)fluorene,2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene,2-(2,2,3,3,4,4,5,5-octafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)pentyl)fluorene,2-(2,2,3,3,4,4-pentafluoro-1-(2-(cyclohexanecaronyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)butyl)fluorene,and2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene.

When the photoacid generator (E) is added to the ArF immersionlithography resist composition, preference is given to sulfonium saltsand oxime-O-sulfonates. Illustrative preferred photoacid generatorsinclude triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfoniumtridecafluorohexanesulfonate, triphenylsulfoniumheptadecafluorooctanesulfonate, triphenylsulfoniumperfluoro(4-ethylcyclohexane)sulfonate, 4-methylphenyldiphenylsulfoniumnonafluorobutanesulfonate, 2-oxo-2-phenylethylthiacyclopentaniumnonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfoniumnonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfoniumperfluoro(4-ethylcyclohexane)sulfonate,4-tert-butylphenyldiphenylsulfonium heptafluorooctanesulfonate,triphenylsulfonium 1,1-difluoro-2-naphthylethanesulfonate,triphenylsulfonium1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,triphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate,triphenylsulfonium2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate,triphenylsulfonium1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,triphenylsulfonium methoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfonium2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfonium2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate,4-tert-butylphenyldiphenylsulfoniumadamantanemethoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfonium1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate,4-tert-butylphenyldiphenylsulfoniummethoxycarbonyldifluoromethanesulfonate,2-oxo-2-phenylethylthiacyclopentanium2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate,2-oxo-2-phenylethylthiacyclopentanium2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate,triphenylsulfonium perfluoro(1,3-propylenebissulfonyl)imide,triphenylsulfonium bis(pentafluoroethylsulfonyl)imide,2-(2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl)fluorene,2-(2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl)fluorene,2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene,2-(2,2,3,3,4,4,5,5-octafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)pentyl)fluorene,2-(2,2,3,3,4,4-pentafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)butyl)fluorene,and2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene.

In the chemically amplified resist composition, the photoacid generator(E) may be added in any desired amount as long as the objects of theinvention are not compromised. An appropriate amount of the photoacidgenerator (E) is 0 to 10 parts, and when added, 0.1 to 10 parts, andmore preferably 0.1 to 5 parts by weight per 100 parts by weight of thebase resin in the composition. Too high a proportion of the photoacidgenerator (E) may give rise to problems of degraded resolution andforeign matter upon development and resist film peeling. The photoacidgenerators (E) may be used alone or in admixture of two or more. Thetransmittance of the resist film can be controlled by using an photoacidgenerator having a low transmittance at the exposure wavelength andadjusting the amount of the photoacid generator added.

It is noted that an acid diffusion controlling function may be providedwhen two or more photoacid generators are used in admixture providedthat one photoacid generator is an onium salt capable of generating aweak acid. Specifically, in a system using a mixture of a photoacidgenerator capable of generating a strong acid (e.g., fluorinatedsulfonic acid) and an onium salt capable of generating a weak acid(e.g., non-fluorinated sulfonic acid or carboxylic acid), if the strongacid generated from the photoacid generator upon exposure to high-energyradiation collides with the unreacted onium salt having a weak acidanion, then a salt exchange occurs whereby the weak acid is released andan onium salt having a strong acid anion is formed. In this course, thestrong acid is exchanged into the weak acid having a low catalysis,incurring apparent deactivation of the acid for enabling to control aciddiffusion.

If an onium salt capable of generating a strong acid and an onium saltcapable of generating a weak acid are used in admixture, an exchangefrom the strong acid to the weak acid as above can take place, but itnever happens that the weak acid collides with the unreacted onium saltcapable of generating a strong acid to induce a salt exchange. This isbecause of a likelihood of an onium cation forming an ion pair with astronger acid anion.

In the resist composition of the invention, there may be added acompound which is decomposed with an acid to generate another acid, thatis, acid amplifier compound. For these compounds, reference should bemade to J. Photopolym. Sci. and Tech., 8, 43-44, 45-46 (1995), andibid., 9, 29-30 (1996).

Examples of the acid amplifier compound includetert-butyl-2-methyl-2-tosyloxymethyl acetoacetate and2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane, but are not limited thereto.Of well-known photoacid generators, many of those compounds having poorstability, especially poor thermal stability exhibit an acidamplifier-like behavior.

In the resist composition of the invention, an appropriate amount of theacid amplifier compound is up to 2 parts, and especially up to 1 part byweight per 100 parts by weight of the base resin. Excessive amounts ofthe acid amplifier compound make diffusion control difficult, leading todegradation of resolution and pattern profile.

Component F

Component (F) is an organic acid derivative and/or a fluorinatedalcohol. Illustrative, non-limiting, examples of the organic acidderivatives include phenol, cresol, catechol, resorcinol, pyrogallol,phloroglucin, bis(4-hydroxyphenyl)methane,2,2-bis(4′-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone,1,1,1-tris(4′-hydroxyphenyl)ethane, 1,1,2-tris(4′-hydroxyphenyl)ethane,hydroxybenzophenone, 4-hydroxyphenylacetic acid, 3-hydroxyphenylaceticacid, 2-hydroxyphenylacetic acid, 3-(4-hydroxyphenyl)propionic acid,3-(2-hydroxyphenyl)propionic acid, 2,5-dihydroxyphenylacetic acid,3,4-dihydroxyphenylacetic acid, 1,2-phenylenediacetic acid,1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid,1,2-phenylenedioxydiacetic acid, 1,4-phenylenedipropanoic acid, benzoicacid, salicylic acid, 4,4-bis(4′-hydroxyphenyl)valeric acid,4-tert-butoxyphenylacetic acid, 4-(4-hydroxyphenyl)butyric acid,3,4-dihydroxymandelic acid, and 4-hydroxymandelic acid. Of these,salicylic acid and 4,4-bis(4′-hydroxyphenyl)valeric acid are preferred.They may be used alone or in admixture of two or more.

The fluorinated alcohol is an alcohol which is substituted with fluorineatoms except α-position. Those compounds terminated with1,1,1,3,3,3-hexafluoro-2-propanol are desirable although the fluorinatedalcohols are not limited thereto. Illustrative examples of the desirablefluorinated alcohols are given below.

Note that R′ is selected from C₂-C₃₀ acetal groups and C₄-C₃₀ tertiarylalkyl groups having formulae (C1) and (C2) which have been described inthe “base resin” section.

In the chemically amplified resist composition of the invention, theorganic acid derivative or fluorinated alcohol is preferably formulatedin an amount of up to 5 parts, and especially up to 1 part by weight,per 100 parts by weight of the base resin. More than 5 phr may result intoo low a resolution. Depending on the combination of the othercomponents in the resist composition, the organic acid derivative andfluorinated alcohol may be omitted.

Component G

In one preferred embodiment, the resist composition further contains (G)a compound with a weight average molecular weight of up to 3,000 whichchanges its solubility in an alkaline developer under the action of anacid, that is, a dissolution inhibitor. Typically, a compound obtainedby substituting acid labile substituents for some or all hydrogen atomsof hydroxyl groups on a phenol or carboxylic acid derivative having alow molecular weight of up to 2,500 or fluorinated alcohol is added asthe dissolution inhibitor.

Examples of the phenol or carboxylic acid derivative having a weightaverage molecular weight of up to 2,500 include bisphenol A, bisphenolH, bisphenol S, 4,4-bis(4′-hydroxyphenyl)valeric acid,tris(4-hydroxyphenyl)methane, 1,1,1-tris(4′-hydroxyphenyl)ethane,1,1,2-tris(4′-hydroxyphenyl)ethane, phenolphthalein, thymolphthalein,cholic acid, deoxycholic acid, and lithocholic acid. Examples of thefluorinated alcohol include compounds terminated with1,1,1,3,3,3-hexafluoro-2-propanol as described above. The acid labilesubstituents are the same as those exemplified as the acid labile groupsin the polymer.

Illustrative, non-limiting, examples of the dissolution inhibitors whichare useful herein include bis(4-(2′-tetrahydropyranyloxy)phenyl)methane,bis(4-(2′-tetrahydrofuranyloxy)phenyl)methane,bis(4-tert-butoxyphenyl)methane,bis(4-tert-butoxycarbonyloxyphenyl)methane,bis(4-tert-butoxycarbonylmethyloxyphenyl)methane,bis(4-(1′-ethoxyethoxy)phenyl)methane,bis(4-(1′-ethoxypropyloxy)phenyl)methane,2,2-bis(4′-(2″-tetrahydropyranyloxy))propane,2,2-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)propane,2,2-bis(4′-tert-butoxyphenyl)propane,2,2-bis(4′-tert-butoxycarbonyloxyphenyl)propane,2,2-bis(4-tert-butoxycarbonylmethyloxyphenyl)propane,2,2-bis(4′-(1″-ethoxyethoxy)phenyl)propane,2,2-bis(4′-(1″-ethoxypropyloxy)phenyl)propane, tert-butyl4,4-bis(4′-(2″-tetrahydropyranyloxy)phenyl)valerate, tert-butyl4,4-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)valerate, tert-butyl4,4-bis(4′-tert-butoxyphenyl)valerate, tert-butyl4,4-bis(4-tert-butoxycarbonyloxyphenyl)valerate, tert-butyl4,4-bis(4′-tert-butoxycarbonylmethyloxyphenyl)valerate, tert-butyl4,4-bis(4′-(1″-ethoxyethoxy)phenyl)valerate, tert-butyl4,4-bis(4′-(1″-ethoxypropyloxy)phenyl)valerate,tris(4-(2′-tetrahydropyranyloxy)phenyl)methane,tris(4-(2′-tetrahydrofuranyloxy)phenyl)methane,tris(4-tert-butoxyphenyl)methane,tris(4-tert-butoxycarbonyloxyphenyl)methane,tris(4-tert-butoxycarbonyloxymethylphenyl)methane,tris(4-(1′-ethoxyethoxy)phenyl)methane,tris(4-(1′-ethoxypropyloxy)phenyl)methane,1,1,2-tris(4′-(2″-tetrahydropyranyloxy)phenyl)ethane,1,1,2-tris(4′-(2″-tetrahydrofuranyloxy)phenyl)ethane,1,1,2-tris(4′-tert-butoxyphenyl)ethane,1,1,2-tris(4′-tert-butoxycarbonyloxyphenyl)ethane,1,1,2-tris(4′-tert-butoxycarbonylmethyloxyphenyl)ethane,1,1,2-tris(4′-(1′-ethoxyethoxy)phenyl)ethane,1,1,2-tris(4′-(1′-ethoxypropyloxy)phenyl)ethane, tert-butyl cholate,tert-butyl deoxycholate, and tert-butyl lithocholate. The compoundsdescribed in JP-A 2003-107706 are also useful.

In the resist composition of the invention, an appropriate amount of thedissolution inhibitor (G) is up to 20 parts, and especially up to 15parts by weight per 100 parts by weight of the base resin. With morethan 20 phr of the dissolution inhibitor, the resist composition becomesless heat resistant because of an increased content of monomercomponents.

Component C′

The base resin used in the negative working resist composition is (C′) abase resin which is normally alkali soluble, but becomes substantiallyalkali insoluble under the action of a crosslinker. It is preferably aprecursor resin which will be substituted with acid labile groups toform the base resin (C).

Examples of the alkali-soluble resin include poly(p-hydroxystyrene),poly(m-hydroxystyrene), poly(4-hydroxy-2-methylstyrene),poly(4-hydroxy-3-methylstyrene), poly(α-methyl-p-hydroxystyrene),partially hydrogenated p-hydroxystyrene copolymers,p-hydroxystyrene-α-methyl-p-hydroxystyrene copolymers,p-hydroxystyrene-α-methylstyrene copolymers, p-hydroxystyrene-styrenecopolymers, p-hydroxystyrene-m-hydroxystyrene copolymers,p-hydroxystyrene-styrene copolymers, p-hydroxystyrene-acrylic acidcopolymers, p-hydroxystyrene-methacrylic acid copolymers,p-hydroxystyrene-methyl methacrylate copolymers,p-hydroxystyrene-acrylic acid-methyl methacrylate copolymers,p-hydroxystyrene-methyl acrylate copolymers,p-hydroxystyrene-methacrylic acid-methyl methacrylate copolymers,poly(methacrylic acid), poly(acrylic acid), acrylic acid-methyl acrylatecopolymers, methacrylic acid-methyl methacrylate copolymers, acrylicacid-maleimide copolymers, methacrylic acid-maleimide copolymers,p-hydroxystyrene-acrylic acid-maleimide copolymers, andp-hydroxystyrene-methacrylic acid-maleimide copolymers, but are notlimited to these combinations.

To impart a certain function, suitable substituent groups may beintroduced into some of the phenolic hydroxyl and carboxyl groups on theforegoing polymer (to be protected with acid labile groups). Exemplaryand preferred are substituent groups for improving adhesion to thesubstrate, substituent groups for improving etching resistance, andespecially substituent groups which are relatively stable against acidand alkali and effective for controlling such that the dissolution ratein an alkali developer of unexposed and low exposed areas of a resistfilm may not become too high. Illustrative, non-limiting, substituentgroups include 2-hydroxyethyl, 2-hydroxypropyl, methoxymethyl,methoxycarbonyl, ethoxycarbonyl, methoxycarbonylmethyl,ethoxycarbonylmethyl, 4-methyl-2-oxo-4-oxolanyl,4-methyl-2-oxo-4-oxanyl, methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, acetyl, pivaloyl, adamantyl, isobornyl, and cyclohexyl. It isalso possible to introduce acid-decomposable substituent groups such astert-butoxycarbonyl and relatively acid-undecomposable substituentgroups such as tert-butyl and tert-butoxycarbonylmethyl.

In the resist composition, the resin (C′) is blended in any desiredamount, preferably of 65 to 99 parts by weight, especially 65 to 98parts by weight per 100 parts by weight of the solids (inclusive of thatresin).

Component H

Formulated in the negative resist composition is a crosslinker (F) whichforms a crosslinked structure under the action of acid. Typicalcrosslinkers are compounds having at least two hydroxymethyl,alkoxymethyl, epoxy or vinyl ether groups within a molecule. Substitutedglycoluril derivatives, urea derivatives, andhexa(methoxymethyl)melamine compounds are suitable as the crosslinker.Examples include N,N,N′,N′-tetramethoxymethylurea,hexamethoxymethylmelamine, tetraalkoxymethyl-substituted glycolurilcompounds such as tetrahydroxymethyl-substituted glycoluril andtetramethoxymethylglycoluril, and condensates of phenolic compounds suchas substituted or unsubstituted bis(hydroxymethylphenol) compounds andbisphenol A with epichlorohydrin. Especially preferred crosslinkers are1,3,5,7-tetraalkoxymethylglycolurils such as1,3,5,7-tetramethoxymethylglycoluril,1,3,5,7-tetrahydroxymethylglycoluril, 2,6-dihydroxymethyl-p-cresol,2,6-dihydroxymethylphenol, 2,2′,6,6′-tetrahydroxymethyl-bisphenol A,1,4-bis[2-(2-hydroxypropyl)]benzene, N,N,N′,N′-tetramethoxymethylurea,and hexamethoxymethylmelamine.

In the chemically amplified resist composition, an appropriate amount ofthe crosslinker is, though not limited thereto, 1 to 20 parts, andespecially 5 to 15 parts by weight per 100 parts by weight of the baseresin. The crosslinkers may be used alone or in admixture of two ormore.

In the chemically amplified resist composition of the invention, theremay be added such additives as a surfactant for improving coatingcharacteristics, and a light absorbing agent for reducing diffusereflection from the substrate.

Illustrative, non-limiting, examples of the surfactant include nonionicsurfactants, for example, polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether,polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenolether and polyoxyethylene nonylphenol ether, polyoxyethylenepolyoxypropylene block copolymers, sorbitan fatty acid esters such assorbitan monolaurate, sorbitan monopalmitate, and sorbitan monostearate,and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylenesorbitan monolaurate, polyoxyethylene sorbitan monopalmitate,polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitantrioleate, and polyoxyethylene sorbitan tristearate; fluorochemicalsurfactants such as EFTOP EF301, EF303 and EF352 (JEMCO Inc.), MegafaceF171, F172, F173, R08 and R30 (Dai-Nippon Ink & Chemicals, Inc.),Fluorad FC430, FC431, FC-4430 and FC-4432 (Sumitomo 3M Co., Ltd.),Asahiguard AG710, Surflon S-381, S-382, SC101, SC102, SC103, SC104,SC105, SC106, Surfynol E1004, KH-10, KH-20, KH-30 and KH-40 (Asahi GlassCo., Ltd.); organosiloxane polymers KP341, X-70-092 and X-70-093(Shin-Etsu Chemical Co., Ltd.), acrylic acid or methacrylic acidPolyflow No. 75 and No. 95 (Kyoeisha Ushi Kagaku Kogyo Co., Ltd.). Interalia, FC430, Surflon S-381, Surfynol E1004, KH-20 and KH-30 arepreferred. These surfactants may be used alone or in admixture.

In the chemically amplified resist composition of the invention, thesurfactant is preferably formulated in an amount of up to 2 parts, andespecially up to 1 part by weight, per 100 parts by weight of the baseresin.

In the chemically amplified resist composition of the invention, a UVabsorber may be added. Those UV absorbers described in JP-A 11-190904are useful, but the invention is not limited thereto. Exemplary UVabsorbers are diaryl sulfoxide derivatives such asbis(4-hydroxyphenyl)sulfoxide, bis(4-tert-butoxyphenyl)sulfoxide,bis(4-tert-butoxycarbonyloxyphenyl)sulfoxide, andbis[4-(1-ethoxyethoxy)phenyl]sulfoxide; diarylsulfone derivatives suchas bis(4-hydroxyphenyl)sulfone, bis(4-tert-butoxyphenyl)sulfone,bis(4-tert-butoxycarbonyloxyphenyl)sulfone,bis[4-(1-ethoxyethoxy)phenyl]sulfone, andbis[4-(1-ethoxypropoxy)phenyl]sulfone; diazo compounds such asbenzoquinonediazide, naphthoquinonediazide, anthraquinonediazide,diazofluorene, diazotetralone, and diazophenanthrone; quinonediazidogroup-containing compounds such as complete or partial ester compoundsbetween naphthoquinone-1,2-diazido-5-sulfonic acid chloride and2,3,4-trihydroxybenzophenone and complete or partial ester compoundsbetween naphthoquinone-1,2-diazido-4-sulfonic acid chloride and2,4,4′-trihydroxybenzophenone; tert-butyl 9-anthracenecarboxylate,tert-amyl 9-anthracenecarboxylate, tert-methoxymethyl9-anthracenecarboxylate, tert-ethoxyethyl 9-anthracenecarboxylate,2-tert-tetrahydropyranyl 9-anthracenecarboxylate, and2-tert-tetrahydrofuranyl 9-anthracenecarboxylate.

The UV absorber may or may not be added to the resist compositiondepending on the type of resist composition. An appropriate amount of UVabsorber, if added, is 0 to 10 parts, more preferably 0.5 to 10 parts,most preferably 1 to 5 parts by weight per 100 parts by weight of thebase resin.

For the microfabrication of integrated circuits, any well-knownlithography may be used to form a resist pattern from the chemicallyamplified resist composition of the invention. The composition isapplied onto a substrate for integrated circuitry fabrication (e.g., Si,SiO₂, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective film, etc.)or a substrate for mask circuitry fabrication (e.g., Cr, CrO, CrON,MoSi, etc.) by a suitable coating technique such as spin coating, rollcoating, flow coating, dip coating, spray coating or doctor coating. Thecoating is prebaked on a hot plate at a temperature of 60 to 150° C. forabout 1 to 10 minutes, preferably 80 to 140° C. for 1 to 5 minutes. Theresulting resist film is generally 0.1 to 2.0 μm thick. Through aphotomask having a desired pattern, the resist film is then exposed toradiation, preferably having an exposure wavelength of up to 300 nm,such as UV, deep-UV, electron beam, EUV, x-ray, excimer laser light,γ-ray and synchrotron radiation. The preferred light source is a beamfrom an excimer laser, especially KrF excimer laser, deep UV of 245-255nm wavelength and ArF excimer laser. The exposure dose is preferably inthe range of about 1 to 200 mJ/cm², more preferably about 10 to 100mJ/cm². The film is further baked on a hot plate at 60 to 150° C. for 1to 5 minutes, preferably 80 to 140° C. for 1 to 3 minutes (post-exposurebaking=PEB).

Thereafter the resist film is developed with a developer in the form ofan aqueous base solution, for example, 0.1 to 5 wt %, preferably 2 to 3wt % aqueous solution of tetramethylammonium hydroxide (TMAH) for 0.1 to3 minutes, preferably 0.5 to 2 minutes by conventional techniques suchas dip, puddle or spray technique. In this way, a desired resist patternis formed on the substrate. It is appreciated that the resistcomposition of the invention is best suited for micro-patterning usingsuch actinic radiation as deep UV with a wavelength of 254 to 193 nm,vacuum UV with a wavelength of 157 nm, electron beam, x-ray, excimerlaser light, γ-ray and synchrotron radiation. With any of theabove-described parameters outside the above-described range, theprocess may sometimes fail to produce the desired pattern.

In the practice of the invention, the immersion lithography processinvolving using ArF excimer laser of 193 nm wavelength and feeding aliquid such as water, glycerin or ethylene glycol between the substrateand the projection lens is advantageously applicable.

EXAMPLE

Synthesis Examples, Examples and Comparative Examples are given belowfor further illustrating the invention, but they are not to be construedas limiting the invention.

Synthesis Example 1 Synthesis of triphenylsulfonium chloride

Diphenyl sulfoxide, 40 g (0.2 mole), was dissolved in 400 g ofdichloromethane, which was stirred under ice cooling. At a temperaturebelow 20° C., 65 g (0.6 mole) of trimethylsilyl chloride was addeddropwise to the solution, which was aged for 30 minutes at thetemperature. Then, a Grignard reagent which had been prepared from 14.6g (0.6 mole) of metallic magnesium, 67.5 g (0.6 mole) of chlorobenzeneand 168 g of tetrahydrofuran (THF) was added dropwise at a temperaturebelow 20° C. The reaction solution was aged for one hour, after which 50g of water at a temperature below 20° C. was added to quench thereaction. To this solution, 150 g of water, 10 g of 12N hydrochloricacid, and 200 g of diethyl ether were further added.

The water layer was separated and washed with 100 g of diethyl ether,yielding an aqueous solution of triphenylsulfonium chloride. Thecompound in aqueous solution form was used in the subsequent reactionwithout further isolation.

Synthesis Example 2 Synthesis of 4-tert-butylphenyldiphenylsulfoniumbromide

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using 4-tert-butylbromobenzene instead of thechlorobenzene in Synthesis Example 1 and increasing the amount of waterfor extraction.

Synthesis Example 3 Synthesis of 4-tert-butoxyphenyldiphenylsulfoniumchloride

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using 4-tert-butoxychlorobenzene instead of thechlorobenzene in Synthesis Example 1, using dichloromethane containing 5wt % of triethylamine as the solvent, and increasing the amount of waterfor extraction.

Synthesis Example 4 Synthesis of tris(4-methylphenyl)sulfonium chloride

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using bis(4-methylphenyl)sulfoxide instead of thediphenyl sulfoxide and 4-chlorotoluene instead of the chlorobenzene inSynthesis Example 1, and increasing the amount of water for extraction.

Synthesis Example 5 Synthesis of tris(4-tert-butylphenyl)sulfoniumbromide

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using bis(4-tert-butylphenyl)sulfoxide instead ofthe diphenyl sulfoxide and 4-tert-butylbromobenzene instead of thechlorobenzene in Synthesis Example 1, and increasing the amount of waterfor extraction.

Synthesis Example 6 Synthesis of bis(4-tert-butylphenyl)iodoniumhydrogen sulfate

A mixture of 84 g (0.5 mole) of tert-butylbenzene, 53 g (0.25 mole) ofpotassium iodate and 50 g of acetic anhydride was stirred under icecooling, and a mixture of 35 g of acetic anhydride and 95 g of conc.sulfuric acid was added dropwise at a temperature below 30° C. Theresulting solution was aged for 3 hours at room temperature and icecooled again, after which 250 g of water was added dropwise to quenchthe reaction. The reaction solution was extracted with 400 g ofdichloromethane. The organic layer was discolored by adding 6 g ofsodium hydrogen sulfite. The organic layer was washed with 250 g ofwater three times. The washed organic layer was concentrated in vacuum,obtaining a crude target product. The product was used in the subsequentreaction without further purification.

Synthesis Example 7 Synthesis of Phenacyltetrahydrothiophenium Bromide

88.2 g (0.44 mole) of phenacyl bromide and 39.1 g (0.44 mole) oftetrahydrothiophene were dissolved in 220 g of nitromethane, which wasstirred for 4 hours at room temperature. 800 g of water and 400 g ofdiethyl ether were added to the reaction solution whereupon the mixtureseparated into two layers. The aqueous layer was taken out, which was anaqueous solution of the target compound, phenacyltetrahydrothiopheniumbromide.

Synthesis Example 8 Synthesis of Dimethylphenylsulfonium HydrogenSulfate

6.2 g (0.05 mole) of thioanisole and 6.9 g (0.055 mole) of dimethylsulfate were stirred for 12 hours at room temperature. 100 g of waterand 50 ml of diethyl ether were added to the reaction solution whereuponthe mixture separated into two layers. The aqueous layer was taken out,which was an aqueous solution of the target compound,dimethylphenylsulfonium hydrogen sulfate.

Synthesis Example 9 Synthesis of sodium2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate

10.0 g of 1,1,3,3,3-pentafluoro-2-propan-2-yl benzoate, which had beensynthesized by a conventional technique, was dispersed in 72 g of water,after which 12.0 g of sodium hydrogen sulfite and 1.24 g of benzoylperoxide were added. The mixture was allowed to react at 85° C. for 65hours. It was cooled and combined with toluene, followed by separatoryoperation to separate a water layer. A saturated sodium chloride aqueoussolution was added to the water layer whereupon white crystals settledout. The crystals were collected by filtration, washed with a smallvolume of saturated sodium chloride aqueous solution and then dried invacuum, obtaining the target compound, sodium2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate. White crystals,5.85 g (yield 43%).

Synthesis Example 10 Synthesis of triphenylsulfonium2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate

To 50 g of dichloromethane were added an amount (corresponding to 0.011mole) of the triphenylsulfonium chloride aqueous solution of SynthesisExample 1 and 3.6 g (0.01 mole) of sodium2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate synthesized inSynthesis Example 9, followed by stirring. The organic layer wasseparated and washed with 50 g of water three times. The organic layerwas concentrated and 25 g of diethyl ether was added to the residue forcrystallization. The crystals were filtered and dried, obtaining thetarget compound. White crystals, 4.5 g (yield 75%).

Synthesis Example 11 Synthesis of triphenylsulfonium2-hydroxy-1,1,3,3,3-pentafluoropropane-1-sulfonate (PAG1)

In 72 g of methanol was dissolved 34.4 g of triphenylsulfonium2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate synthesized inSynthesis Example 10. While the solution was stirred under ice cooling,54.0 g of 5% sodium hydroxide solution was added dropwise at atemperature below 10° C. It was aged at the temperature for 4 hours. Ata temperature below 10° C., 6.8 g of 12N hydrochloric acid was added toquench the reaction. The methanol was distilled off in vacuum, afterwhich 270 g of dichloromethane was added to the residue. The organiclayer was washed with 40 g of water three times. The organic layer wasconcentrated, after which 60 g of diethyl ether was added to the residuefor crystallization. The crystals were filtered and dried, obtaining thetarget compound. White crystals, 24.3 g (yield 85%).

Synthesis Examples 12-18

Target compounds were synthesized as in Synthesis Examples 10 and 11except that the sulfonium salts prepared in Synthesis Examples 2 to 8were used. The resulting onium salts PAG2 to PAG8 are shown below.

Synthesis Example 19 Synthesis of triphenylsulfoniumhydrogen/1-(difluorosulfomethyl)-2,2,2-trifluoroethylcyclohexane-1,2-dicarboxylate (PAG-A)

In 20 g of acetonitrile were dissolved 4.9 g (0.01 mole) oftriphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropane-1-sulfonate ofSynthesis Example 11, 1.0 g (0.01 mole) of triethylamine, and 0.24 g(0.002 mole) of N,N-dimethylaminopyridine. 1.85 g (0.012 mole) ofcis-cyclohexane-1,2-dicarboxylic anhydride was added to the solution,which was heated and stirred at 50° C. for 24 hours. A dilutehydrochloric acid solution prepared from 2 g of 12N hydrochloric acidand 20 g of water was added, after which acetonitrile was distilled offin vacuum. 50 g of dichloromethane and 20 g of water were added to theresidue, whereupon the organic layer was separated. The organic layerwas then washed with 20 g of water, after which dichloromethane wasdistilled off in vacuum. Ether was added to the residue for purificationby recrystallization. Filtration and drying gave the target compound.White crystals, 3.8 g (yield 59%).

The target compound was analyzed by spectroscopy. The data of infrared(IR) absorption spectroscopy and time-of-flight mass spectrometry(TOFMS) are shown below. The NMR spectra, ¹H-NMR and ¹⁹F-NMR in DMSO-d₆are shown in FIGS. 1 and 2.

IR spectra (KBr, cm⁻¹) 3066, 2940, 2859, 1768, 1733, 1477, 1448, 1371,1326, 1276, 1251, 1232, 1189, 1166, 1145, 1112, 1074, 995, 750, 682,642, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻383(corresponding to CF₃CH(OCO—C₆H₁₀—CO₂H)CF₂SO₃ ⁻)

Synthesis Example 20 Synthesis of triphenylsulfoniumcyclohexyl/1-(difluorosulfomethyl)-2,2,2-trifluoroethylbicyclo[2.2.1]heptane-2,3-dicarboxylate (PAG-B)

In 20 g of acetonitrile were dissolved 4.9 g (0.01 mole) oftriphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropane-1-sulfonate ofSynthesis Example 11, 1.0 g (0.01 mole) of triethylamine, and 0.24 g(0.002 mole) of N,N-dimethylaminopyridine. This was ice cooled. 3.4 g(0.012 mole) of 3-cyclohexyloxycarbonylbicyclo[2.2.1]heptane-2-carbonylchloride was added to the solution at a temperature below 5° C. Thesolution was stirred for 1 hour at room temperature. A dilutehydrochloric acid solution prepared from 1 g of 12N hydrochloric acidand 10 g of water was added, after which acetonitrile was distilled offin vacuum. 100 g of dichloromethane and 20 g of water were added to theresidue, whereupon the organic layer was separated. The organic layerwas then washed with 20 g of water, after which dichloromethane wasdistilled off in vacuum. The steps of adding ether to the residue anddecanting a separating oily matter were repeated three times. The oilymatter was vacuum evaporated to dryness, obtaining 5.8 g of the targetcompound in a vitreous solid form (yield 82%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 3 and 4.

IR spectra (KBr, cm⁻¹) 2940, 1762, 1720, 1477, 1448, 1371, 1265, 1251,1214, 1184, 1116, 1087, 1072, 995, 750, 684, 642, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻383(corresponding to CF₃CH(OCO—C₇H₁₀—CO₂C₆H₁₁)CF₂SO₃ ⁻)

Synthesis Example 21 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,2-trifluoroethylhexahydro-3,5-methano-2H-cyclopenta-[b]furan-2-oxo-7-carboxylate (PAG-C)

The procedure of Synthesis Example 20 was repeated except that 2.0 g(0.01 mole) ofhexahydro-3,5-methano-2-oxo-2H-cyclopenta[b]furan-7-carboxylic acidchloride was used instead of the3-cyclohexyloxycarbonylbicyclo[2.2.1]heptane-2-carbonyl chloride. Thetarget compound was obtained in a vitreous solid form.

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 5 and 6.

IR spectra (KBr, cm⁻¹) 2973, 1779, 1477, 1448, 1369, 1315, 1253, 1216,1186, 1166, 1135, 1101, 1087, 1070, 1035, 995, 983, 950, 840, 750, 684,640, 578, 551, 522, 501

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻383(corresponding to CF₃CH(OCO—C₈H₉O₂)CF₂SO₃ ⁻)

Specifically, PAG-A, PAG-B, and PAG-C have the structure shown below.

It is noted that PAG-A has in its anion moiety acyclohexane-1,2-dicarboxylic acid derivative which includes cis andtrans forms. PAG-B has in its anion moiety abicyclo[2.2.1]heptane-2,3-dicarboxylic acid derivative which includestwo endo- or exo-assuming positions. PAG-C has ahexahydro-3,5-methano-2H-cyclopenta[b]furan-2-oxo-7-carboxylic acidderivative which includes one endo- or exo-assuming position. Analysisresults show that PAG-A, PAG-B, and PAG-C each are a mixture of isomers.

The photoacid generator of the invention may be composed of a singlecompound or an isomer mixture.

Synthesis Examples 22 to 42

PAG-D to PAG-X of the structure shown below were synthesized by the sameprocedure as in Synthesis Examples 19 to 21, aside from using PAG2 toPAG8 of Synthesis Examples 12 to 18.

Synthesis Example 43 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,22-trifluoroethyl4-adamantanone-1-carboxylate (PAG-Y)

4-adamantanone-1-carboxylic acid was synthesized by reaction of5-hydroxy-2-adamantanone with sulfuric acid and formic acid. Usingoxalyl chloride, it was converted into a corresponding carboxylic acidchloride.

In 20 g of acetonitrile were dissolved 4.9 g (0.01 mole) oftriphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropane-1-sulfonate ofSynthesis Example 11, 1.0 g (0.01 mole) of triethylamine, and 0.24 g(0.002 mole) of N,N-dimethylaminopyridine. This was ice cooled. 2.6 g(0.012 mole) of 4-adamantanone-1-carbonyl chloride, prepared above, wasadded to the solution at a temperature below 5° C. The solution wasstirred for 1 hour at room temperature. A dilute hydrochloric acidsolution prepared from 1 g of 12N hydrochloric acid and 10 g of waterwas added, after which acetonitrile was distilled off in vacuum. 50 g ofdichloromethane, 50 g of methyl isobutyl ketone and 20 g of water wereadded to the residue, whereupon the organic layer was separated. Theorganic layer was then washed with 20 g of water, after which thesolvents were distilled off in vacuum. The steps of adding ether to theresidue and decanting a separating oily matter were repeated threetimes. The oily matter was vacuum evaporated to dryness, obtaining 4.3 gof the target compound in an oily form (yield 65%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 7 and 8. It wasobserved in ¹H-NMR that traces of dichloromethane and methyl isobutylketone were left.

IR spectra (KBr, cm⁻¹) 2937, 2861, 1758, 1724, 1687, 1477, 1448, 1373,1326, 1251, 1218, 1186, 1162, 1089, 1074, 1033, 995, 917, 750, 684, 640,574, 551, 516, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻405(corresponding to (C₁₀H₁₃O—COO)CH(CF₃)CF₂SO₃ ⁻)

PAG-Y has the structure shown below.

Synthesis Example 44 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,2-trifluoroethyl phthalic acid (PAG-Z1)

In 20 g of tetrahydrofuran were dissolved 4.9 g (0.01 mole) oftriphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropane-1-sulfonate ofSynthesis Example 11. This was cooled by dry ice/methanol bath. 0.01mole of n-butyl lithium hexane solution was added to the solution, andthen 3.0 g (0.02 mole) of phthalic anhydride was added to the solutionat a temperature below 25° C. The solution was stirred for 1 hour atroom temperature. 0.1 g (0.001 mole) ofN,N,N′,N′-tetramethylethylenediamine was added thereto, and the solutionwas further stirred for 1 hour. A dilute hydrochloric acid solutionprepared from 1 g of 12N hydrochloric acid and 10 g of water was added,after which tetrahydrofuran was distilled off in vacuum. 50 g ofdichloromethane, 50 g of methyl isobutyl ketone and 20 g of water wereadded to the residue, whereupon the organic layer was separated. Theorganic layer was then washed with 20 g of water, after which thesolvents were distilled off in vacuum. The steps of adding ether to theresidue and crystallizing were conducted, obtaining 3.4 g of the targetcompound as a white crystal (yield 50%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 9 and 10.

IR spectra (KBr, cm⁻¹) 3064, 2969, 2935, 1772, 1727, 1477, 1448, 1394,1371, 1324, 1280, 1259, 1228, 1193, 1168, 1135, 1110, 1079, 993, 906,777, 754, 748, 684, 642, 580, 553, 522, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻377(corresponding to (C₇H₅O₂—COO)CH(CF₃)CF₂SO₃ ⁻)

PAG-Z1 has the structure shown below.

Synthesis Example 45 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,2-trifluoroethyl succinic acid (PAG-Z2)

The procedure of Synthesis Example 19 was repeated except that succinicanhydride was used instead of cyclohexane-1,2-dicarboxylic anhydride.The target compound was obtained as a white crystal (yield 76%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 11 and 12.

IR spectra (KBr, cm⁻¹) 3093, 3068, 1776, 1733, 1477, 1448, 1421, 1373,1321, 1276, 1238, 1184, 1170, 1128, 1076, 995, 948, 906, 838, 752, 684,642, 512, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻329(corresponding to (C₃H₅O₂—COO)CH(CF₃)CF₂SO₃ ⁻)

PAG-Z2 has the structure shown below.

Synthesis Example 46 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,2-trifluoroethyl3-cyclohexene-1,2-dicarboxylic acid (PAG-Z3)

The procedure of Synthesis Example 19 was repeated except that3-cyclohexene-1,2-dicarboxylic anhydride was used instead ofcyclohexane-1,2-dicarboxylic anhydride. The target compound was obtainedas a white crystal (yield 70%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 13 and 14.

IR spectra (KBr, cm⁻¹) 3064, 2971, 1768, 1735, 1477, 1448, 1371, 1324,1274, 1249, 1224, 1189, 1135, 1072, 995, 750, 684, 642, 503

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻381(corresponding to (C₇H₉O₂—COO)CH(CF₃)CF₂SO₃ ⁻)

PAG-Z3 has the structure shown below.

Synthesis Example 47 Synthesis of triphenylsulfonium1-(difluorosulfomethyl)-2,2,2-trifluoroethyl 4-cyclohexanone-carboxylate(PAG-Z4)

The procedure of Synthesis Example 43 was repeated except that4-cyclohexanone-1-carbonyl chloride was used instead of4-adamantanone-1-carbonyl chloride. The target compound was obtained inan oily form (yield 69%).

The target compound was analyzed by spectroscopy. The data of IRabsorption spectroscopy and TOFMS are shown below. The NMR spectra,¹H-NMR and ¹⁹F-NMR in DMSO-d₆ are shown in FIGS. 15 and 16.

IR spectra (KBr, cm⁻¹) 1766, 1712, 1477, 1448, 1373, 1324, 1251, 1216,1186, 1116, 1072, 995, 925, 875, 838, 750, 684, 642

TOFMS (MALDI) Positive M⁺263 (corresponding to (C₆H₅)₃S⁺) Negative M⁻353(corresponding to (C₆H₉O—COO)CH(CF₃)CF₂SO₃ ⁻)

PAG-Z4 has the structure shown below.

Examples 1-11 & Comparative Examples 1-2 Evaluation of Resist Resolution

Resist compositions were prepared by dissolving the photoacid generatorsof Synthesis Examples, Polymers 1 to 8 as the base resin, and quencherin a solvent containing 0.01 wt % of surfactant KH-20 (Seimi ChemicalCo., Ltd.) according to the formulation shown in Table 1. They werefiltered through a Teflon® filter having a pore size of 0.2 μm, givingresist solutions. Polymers 1 to 8 are shown below.

An antireflective coating liquid ARC-29A (Nissan Chemical Co., Ltd.) wascoated onto a silicon substrate and baked at 200° C. for 60 seconds toform an antireflective coating of 78 nm thick. The resist solution wasspin coated onto the antireflective coating and baked on a hot plate at100° C. for 60 seconds, forming a resist film of 120 nm thick. Theresist film was exposed by means of an ArF excimer laser microsteppermodel NSR-S307E (Nikon Corp., NA 0.85, ⅘ annular illumination, Cr mask),post-exposure baked (PEB) at the temperature shown in Table 2 for 60seconds, and developed with a 2.38 wt % aqueous solution oftetramethylammonium hydroxide (TMAH) for 60 seconds.

An optimal exposure dose (sensitivity Eop, mJ/cm²) was the exposurewhich provided a 1:1 resolution at the top and bottom of a 80-nm groupedline-and-space pattern. The minimum line width (nm) of a line-and-spacepattern which was ascertained separate at this dose was the resolutionof a test resist. For the evaluation of pattern density dependency, a1:10 isolated line pattern with an on-mask size of 130 nm was formed atthe optimum exposure and determined for an actual on-wafer size, whichwas reported as mask fidelity (a larger value of on-wafer size isbetter).

The formulation and test results of the resist compositions are shown inTables 1 and 2, respectively.

The solvents and quenchers in Tables 1 and 2 are shown below as well asthe photoacid generators in Comparative Examples.

-   Solvent A: propylene glycol monomethyl ether acetate-   Solvent B: cyclohexanone-   Quencher A: triethanolamine-   Quencher B: trismethoxymethoxyethylamine-   TPS-NfO: triphenylsulfonium perfluoro-1-butanesulfonate-   TPS-BzOPFPS: triphenylsulfonium    2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate

TABLE 1 Comparative Formulation Example Example (pbw) 1 2 3 4 5 6 7 8 910 11 1 2 Polymer 1 80 60 80 80 Polymer 2 80 40 60 80 Polymer 3 80Polymer 4 80 Polymer 5 40 20 20 Polymer 6 80 Polymer 7 80 Polymer 8 80PAG-A 7.5 7.5 7.5 7.5 5.0 3.8 3.8 PAG-B 8.6 8.6 4.3 PAG-C 7.6 7.6 3.8TPS-NfO 6.5 TPS-BzOPFPS 1.7 5.2 Quencher A 0.75 0.75 0.75 0.75 0.75 0.750.75 0.75 Quencher B 1.41 1.41 1.41 1.41 1.41 Solvent A 800 720 800 800560 800 800 800 720 800 560 Solvent B 80 240 80 240

TABLE 2 Comparative Example Example Tests 1 2 3 4 5 6 7 8 9 10 11 1 2PEB temp. (° C.) 110 110 125 110 100 110 110 110 110 110 110 110 110Sensitivity 30 32 34 32 32 24 25 21 32 30 30 32 30 (mJ/cm²) Resolution(nm) 70 70 75 75 70 75 75 75 75 70 75 75 75 Mask fidelity 80 85 85 85 8570 70 60 75 85 85 30 60

Next, simulative immersion photolithography was carried out using theresist compositions of Examples 1, 4, 9 and Comparative Example 1.Specifically, a resist film of 125 nm thick was formed on a wafer by aprocedure as described above and exposed by means of an ArF excimerlaser microstepper model S307E (Nikon Corp., dipole). Immediately afterthe exposure, deionized water was fed over the entire surface of thewafer, whereby the exposed surface of resist was immersed in deionizedwater for 60 seconds (puddle). The wafer was rotated to spin off thewater, followed by ordinary PEB and development. The number of defectsin the pattern formed after development was counted by a waferinspection system WINWIN 50-1200L (Tokyo Seimitsu Co., Ltd.). A defectdensity was computed therefrom.Defect density (/cm²)=(total number of detected defects)/(test area).

-   Pattern formed: repetitive pattern of 80 mm pitch, 160 nm    line-and-space-   Defect detection: light source UV, detection pixel size 0.125 μm,    cell-to-cell mode

Additionally, the pattern profile in resist cross-section was observedunder a scanning electron microscope. The results are shown in Table 3.

TABLE 3 Pattern profile Defect density (/cm²) Example 1 rectangular≦0.05 Example 4 rectangular ≦0.05 Example 9 rectangular ≦0.05Comparative Example 1 extreme T-top 10  

As is evident from Tables 2 and 3, the resist compositions of theinvention have a high sensitivity, high resolution and minimized patterndensity dependency, and invite neither profile changes nor defectsduring a long term of water rinsing as compared with the prior artcomposition, suggesting an ability to comply with the immersionphotolithography.

Japanese Patent Application No. 2006-263934 is incorporated herein byreference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A photoacid generator for chemically amplified resist compositionswhich generates a sulfonic acid upon exposure to high-energy radiationselected from UV, deep-UV, EUV, electron beam, x-ray, excimer laser,gamma-ray and synchrotron radiation, said sulfonic acid having thegeneral formula (1a):RC(═O)R¹—COOCH(CF₃)CF₂SO₃ ⁻H⁺  (1a) wherein R is selected from the groupconsisting of a hydroxyl group, a substituted or unsubstituted straight,branched or cyclic C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkoxy group, and a substituted orunsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxy group, R¹ is adivalent C₁-C₂₀ organic group which may have a substituent groupcontaining a heteroatom selected from oxygen, nitrogen and sulfur atoms,or R¹ may form at least one cyclic structure with R.
 2. A sulfonium salthaving the general formula (2):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻R²R³R⁴S⁺  (2) wherein R is selected from thegroup consisting of a hydroxyl group, a substituted or unsubstitutedstraight, branched or cyclic C₁-C₂₀ alkyl group, a substituted orunsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, a substituted orunsubstituted straight, branched or cyclic C₁-C₂₀ alkoxy group, and, asubstituted or unsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅ hetero-aryloxygroup, R¹ is a divalent C₁-C₂₀ organic group which may have asubstituent group containing a heteroatom selected from oxygen, nitrogenand sulfur atoms, or R¹ may form at least one cyclic structure with R,R², R³ and R⁴ are each independently selected from the group consistingof substituted or unsubstituted straight, branched or cyclic C₁-C₂₀alkyl, alkenyl and oxoalkyl groups, and substituted or unsubstitutedC₆-C₁₈ aryl, aralkyl and aryloxoalkyl groups, or at least two of R², R³and R⁴ may bond together to form a ring with the sulfur atom.
 3. Asulfonium salt having the general formula (2a):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻(R⁵(O)_(n))_(m)Ph′S⁺Ph₂  (2a) wherein R isselected from the group consisting of a hydroxyl group, a substituted orunsubstituted straight, branched or cyclic C₁-C₂₀ alkyl group, asubstituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkoxygroup, and a substituted or unsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic group which mayhave a substituent group containing a heteroatom selected from oxygen,nitrogen and sulfur atoms, or R¹ may form at least one cyclic structurewith R, R⁵ is a substituted or unsubstituted straight, branched orcyclic C₁-C₂₀ alkyl or alkenyl group, or a substituted or unsubstitutedC₆-C₁₄ aryl group, m is an integer of 1 to 5, n is 0 or 1, Ph is phenyl,and Ph′ is a phenyl group in which a number “m” of hydrogen atoms aresubstituted by R⁵(O)_(n)— groups.
 4. A iodonium salt having the generalformula (2b):RC(═O)—R¹—COOCH(CF₃)CF₂SO₃ ⁻[(R⁵(O)_(n))_(m)Ph′]₂I⁺  (2b) wherein R isselected from the group consisting of a hydroxyl group, a substituted orunsubstituted straight, branched or cyclic C₁-C₂₀ alkyl group, asubstituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-aryl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkoxygroup, and a substituted or unsubstituted C₆-C₁₅ aryloxy or C₄-C₁₅hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic group which mayhave a substituent group containing a heteroatom selected from oxygen,nitrogen and sulfur atoms, or R¹ may form at least one cyclic structurewith R, R⁵ is a substituted or unsubstituted straight, branched orcyclic C₁-C₂₀ alkyl or alkenyl group, or a substituted or unsubstitutedC₆-C₁₄ aryl group, m is an integer of 1 to 5, n is 0 or 1, and Ph′ is aphenyl group in which a number “m” of hydrogen atoms are substituted byR⁵(O)_(n)— groups.
 5. A N-sulfonyloxyimide compound having the generalformula (3a):

wherein R is selected from the group consisting of a hydroxyl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkylgroup, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-arylgroup, a substituted or unsubstituted straight, branched or cyclicC₁-C₂₀ alkoxy group, and a substituted or unsubstituted C₆-C₁₅ aryloxyor C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic groupwhich may have a substituent group containing a heteroatom selected fromoxygen, nitrogen and sulfur atoms, or R¹ may form at least one cyclicstructure with R, X and Y are each independently hydrogen or asubstituted or unsubstituted C₁-C₆ alkyl group, or X and Y may bondtogether to form a saturated or unsaturated C₆-C₁₂ ring with the carbonatoms to which they are attached, and Z is a single bond, double bond,methylene group or oxygen atom.
 6. An oxime sulfonate compound havingthe general formula (3b):

wherein R is selected from the group consisting of a hydroxyl group, asubstituted or unsubstituted straight, branched or cyclic C₁-C₂₀ alkylgroup, a substituted or unsubstituted C₆-C₁₅ aryl or C₄-C₁₅ hetero-arylgroup, a substituted or unsubstituted straight, branched or cyclicC₁-C₂₀ alkoxy group, and a substituted or unsubstituted C₆-C₁₅ aryloxyor C₄-C₁₅ hetero-aryloxy group, R¹ is a divalent C₁-C₂₀ organic groupwhich may have a substituent group containing a heteroatom selected fromoxygen, nitrogen and sulfur atoms, or R¹ may form at least one cyclicstructure with R, q is 0 or 1, when q is 0, p is a substituted orunsubstituted C₁-C₂₀ alkyl group or a substituted or unsubstitutedC₆-C₁₅ aryl group, when q is 1, p is a single bond, a substituted orunsubstituted C₁-C₂₀ alkylene group or a substituted or unsubstitutedC₆-C₁₅ arylene group, EWG is a cyano, trifluoromethyl, perfluoroethyl,perfluoropropyl, 5H-perfluoropentyl, 6H-perfluorohexyl, nitro or methylgroup, and when q is 1, two EWG's may bond together to form a ring of 6carbon atoms with the carbon atoms to which they are attached.
 7. Aresist composition comprising a base resin, an acid generator, and anorganic solvent, said acid generator comprising a photoacid generatorwhich generates a sulfonic acid having formula (1a) as set forth inclaim
 1. 8. The resist composition of claim 7, wherein said base resinis at least one polymer selected from the group consisting ofpoly(meth)acrylic acid and derivatives thereof, cycloolefinderivative/maleic anhydride alternating copolymers, copolymers ofternary or more components comprising a cycloolefin derivative, maleicanhydride, and polyacrylic acid or derivatives thereof, cycloolefinderivative/α-trifluoromethyl acrylate derivative copolymers,polynorbornene, ring-opening metathesis polymers, and hydrogenatedring-opening metathesis polymers.
 9. The resist composition of claim 7,wherein said base resin is a polymeric structure containing siliconatoms.
 10. The resist composition of claim 7, wherein said base resin isa polymeric structure containing fluorine atoms.
 11. A chemicallyamplified positive resist composition comprising a base resin as setforth in claim 8, 9 or 10, a photoacid generator which generates asulfonic acid having formula (1a) as set forth in claim 1, and asolvent, wherein said base resin is insoluble or substantially insolublein a liquid developer, and becomes soluble under the action of the acid.12. The chemically amplified positive resist composition of claim 11,further comprising a quencher.
 13. The chemically amplified positiveresist composition of claim 11, further comprising a dissolutioninhibitor.
 14. A process for forming a pattern comprising the steps of:applying the resist composition of claim 7 onto a substrate to form acoating, heat treating the coating and exposing it to high-energyradiation having a wavelength of up to 300 nm through a photomask, andoptionally heat treating and developing the exposed coating with adeveloper.
 15. The process of claim 14, wherein the exposing step relieson immersion lithography comprising directing radiation from an ArFexcimer laser having a wavelength of 193 nm through a projection lens,with a liquid such as water, glycerin or ethylene glycol interveningbetween the coated substrate and the projection lens.